Internal Audit Services Companies in London: Top Firms List

Choosing an internal audit provider in London isn’t just a box-ticking exercise – it’s a decision that can quietly shape how resilient, compliant, and well-run your organisation becomes over time. The city has no shortage of firms offering internal audit support, from global networks to specialist boutiques, each with its own strengths, sector focus, and working style.

Below, you’ll find a carefully assembled list of internal audit services companies operating in London. Rather than ranking them or making bold claims, this guide is meant to give you grounded context – who these firms are, the types of organisations they typically work with, and what tends to set them apart. 

1. Acumon

Acumon is a London founded firm of chartered accountants, auditors and advisors that provides internal audit services alongside a wider range of audit, risk, tax and advisory support. With offices in West London and clients across the UK and overseas, we operate as a full service practice, supporting organisations with complex financial and governance needs rather than treating internal audit as a standalone activity. In a city like London, where many companies deal with demanding regulation and layered group structures, our work often centres on helping finance leaders maintain oversight, strengthen governance and keep processes aligned with UK requirements.

Our internal audit and assurance work sits within a broader risk and technology offering. We typically work with finance directors, CFOs and boards that want an independent view of how controls, systems and operational risks are being managed. Because our team is entirely UK based and includes people with HMRC and regulatory experience, we tend to approach reviews from a practical compliance perspective, focusing on how things actually function day to day rather than theory alone.

Key Highlights:

• London based firm with UK wide and international client base
• Registered audit practice authorised by professional regulators
• Internal audit delivered as part of broader risk and governance support
• UK based team including professionals with HMRC background
• Experience working with corporates, charities and group subsidiaries
• Combines accounting, audit, tax and advisory capabilities in one firm

Services:

• Internal audit and governance reviews
• Risk management and compliance support
• IT risk and cybersecurity assurance
• External statutory audit
• Accounts preparation and bookkeeping
• Tax planning and compliance
• Business advisory and due diligence
• Payroll and company secretarial support

Contact Information:

• Website: acumon.com
• Email: mail@acumon.com
• Address: 1-2 Craven Road, Ealing, London, W5 2UA, UK
• Phone: 020 8567 3451

2. Harvey Craig

Harvey Craig is based in central London near Oxford Circus, an area filled with firms that operate under tight regulatory expectations. They provide internal audit and risk assurance as part of a wider audit and advisory practice, working with businesses that need an independent look at how their controls and processes actually function. In a city where compliance requirements can shift quickly, their work often focuses on whether organisations are meeting obligations under UK laws such as FCA rules, GDPR and the Companies Act.

Their reviews usually look beyond the numbers alone. They examine operational processes, financial controls and governance arrangements to understand where risks may sit or where procedures are not working as intended. The team includes professionals with regulatory and industry backgrounds, which helps when assessing fraud risks, cybersecurity concerns or sector specific compliance issues. Reports are typically written for management use, with practical observations rather than abstract commentary.

Key Highlights:

• Central London audit and advisory firm
• Internal audit combined with risk assurance work
• Familiar with UK regulatory frameworks
• Experience across regulated industries
• Focus on operational as well as financial risks
• Provides ongoing monitoring and reporting

Services:

• Internal audit reviews
• Risk assessments
• Compliance audits
• Operational and financial process evaluation
• Fraud risk support
• Governance and assurance work

Contact Information:

• Website: harveycraig.co.uk
• Email: info@harveycraig.co.uk
• Twitter: x.com/harveycraiguk
• Instagram: www.instagram.com/harvey_craig_official
• Address: Office # 401, 18 Great Portland Street, London, W1W 8QP
• Phone: +44 20 8145 7393

3. Oasis Accountants

Oasis Accountants operates from Chiswick in West London and mainly serves individuals, landlords and small to mid sized businesses across the city. Their core work sits in accounting and tax, but that often overlaps with internal control and oversight needs, especially for organisations without in house finance teams. In London’s property heavy market, many of their clients are dealing with rental income, company structures and ongoing compliance tasks.

They rely heavily on accounting software and digital tools to manage records and reporting, which can help clients maintain a clearer view of their finances. While they are not a specialist internal audit provider, their involvement in management accounts, compliance and financial supervision can support internal governance, particularly for growing businesses. Much of their work is practical and day to day, keeping finances organised and aligned with reporting requirements.

Key Highlights:

• Chartered accountants based in Chiswick
• Works with individuals, landlords and businesses
• Strong focus on property related finances
• Uses digital accounting systems
• Accredited by professional bodies
• Serves clients locally and nationwide

Services:

• Bookkeeping and accounts preparation
• Tax planning and compliance
• Payroll processing
• Management accounts
• Company formation support
• Personal accounting services

Contact Information:

• Website: oasisaccountants.co.uk
• Email: hello@oasisaccountants.co.uk
• Facebook: www.facebook.com/OasisAccountants
• Twitter: x.com/oasisaccounts
• LinkedIn: www.linkedin.com/company/oasisaccountants
• Instagram: www.instagram.com/oasis_accountant
• Address: Office Gold, Building 7, Floor 5, 566 Chiswick High Road, Chiswick Business Park, London, W4 5YG
• Phone: 0203 818 9530

4. Lighthouse Consultants

Lighthouse Consultants operates from Fitzrovia, a central London area known for advisory and professional firms. They focus specifically on internal audit work, supporting organisations that want an external view of their control environment and operational practices. Many London based companies bring in independent reviewers when internal teams are small or when boards want a neutral assessment.

Their audits are designed to evaluate whether policies, procedures and controls are actually working in practice. This can include checking compliance arrangements, reviewing operational processes and identifying areas where risks are not fully managed. The outcome is usually a structured assessment of the organisation’s internal environment, giving leadership a clearer picture of strengths and gaps.

Key Highlights:

• Central London consultancy focused on internal audit
• Independent assessment of controls and processes
• Supports governance and compliance oversight
• Suitable for organisations without in house audit teams
• Located in a major professional district
• Works across different sectors

Services:

• Internal audit engagements
• Internal control reviews
• Compliance assessments
• Operational process analysis
• Risk identification

Contact Information:

• Website: lighthc.london
• Email: info@lighthc.london
• Facebook: www.facebook.com/people/Lighthouse-Consultants/100063797875484
• LinkedIn: www.linkedin.com/company/lighthouseconsultants
• Instagram: www.instagram.com/lighthouse_consultants
• Address: Fitzrovia, 60 Tottenham Court Road, London, W1T 2EW
• Phone: +44 207 871 0485

5. Walden Way & Co.

Walden Way & Co. is a London firm of chartered accountants and registered auditors that includes internal audit as part of its wider audit services. Their work reflects the needs of businesses operating in a city where transparency and proper governance are closely watched by regulators, lenders and stakeholders. Internal audit is presented as an independent check on financial reporting, internal controls and operational performance.

They review financial records, procedures and compliance with relevant regulations to see whether systems are reliable and functioning as expected. This can involve identifying inconsistencies, control weaknesses or areas where efficiency could be improved. The firm uses partner led teams, which means senior professionals tend to stay closely involved throughout the audit process.

Key Highlights:

• London based chartered accountants and auditors
• Registered audit firm serving UK businesses
• Internal audit linked to governance and transparency
• Independent review of financial and operational systems
• Partner involvement in engagements
• Works across multiple sectors

Services:

• Internal audit reviews
• Financial statement analysis
• Internal control assessments
• Compliance checks
• Risk evaluations
• External audit support

Contact Information:

• Website: www.waldenway.co.uk
• Email: info@waldenway.co.uk
• Facebook: www.facebook.com/people/Walden-Way-Co/61564909815318
• Twitter: x.com/way_walden
• LinkedIn: www.linkedin.com/company/walden-way-&-co-
• Instagram: www.instagram.com/waldenway2024
• Address: Unit A3, Gateway Tower, 32 Western Gateway, London E16 1YL
• Phone: 0203 4411 205

6. Grant Thornton

Grant Thornton has a significant presence in London as part of an international network of professional services firms. Their internal audit work is aimed at organisations with complex structures, large operations or strict regulatory obligations. In a global business hub like London, many companies need assurance that extends across multiple departments, subsidiaries or jurisdictions.

They provide independent reviews through teams that combine audit specialists with subject experts from areas such as technology, risk and governance. Engagements can be structured in different ways, including fully outsourced internal audit functions or support for existing teams during busy periods. The focus is usually on how organisations manage risks, maintain controls and respond to changing business conditions.

Key Highlights:

• UK member of a global professional services network
• Internal audit for complex organisations
• Multidisciplinary teams with specialist expertise
• Flexible delivery models including outsourcing
• Experience across industries
• Works with both UK and international operations

Services:

• Risk based internal audits
• Internal audit outsourcing or co sourcing
• External quality assessments
• Governance and control reviews
• Emerging risk assurance
• Advisory support

Contact Information:

• Website: www.grantthornton.co.uk
• LinkedIn: www.linkedin.com/company/grant-thornton-uk
• Instagram: www.instagram.com/gt_trainees
• Address: 8 Finsbury Circus, London, EC2M 7EA
• Phone: +44 (0)20 7383 5100

7. JR Consultants

JR Consultants provides ISO focused internal audit services to organisations in London that need to maintain or achieve certification standards. Their work centres on management systems, which is different from traditional financial internal audit but still closely tied to compliance and operational reliability. Many businesses in London pursue ISO certification to meet contractual requirements or demonstrate quality standards to partners.

They carry out independent reviews of procedures, policies and day to day practices to check alignment with relevant ISO frameworks. Audits typically involve examining documentation, speaking with staff and observing how processes operate in real settings. The aim is to identify gaps, inefficiencies or non conformities so organisations can adjust before external certification assessments.

Key Highlights:

• Specialist in ISO internal audits
• Focus on management system compliance
• Independent evaluation of procedures and controls
• Supports certification and surveillance audits
• Applicable to organisations of different sizes
• Provides ongoing audit assistance

Services:

• ISO internal audits
• Management system assessments
• Compliance gap analysis
• Audit preparation support
• Documentation review
• Follow up assistance

Contact Information:

• Website: www.jrconsultants.co.uk
• Email: info@jrconsultants.co.uk
• Facebook: www.facebook.com/jrconsultantsfamily
• Address: The Hamilton Centre, Suite 3, First Floor, Rodney Way, Chelmsford, Essex, CM1 3BY
• Phone: 01268 758000

8. Price Bailey

Price Bailey is a chartered accountancy and advisory firm with offices in London and other UK locations. Their internal audit work is often used by organisations that need independent oversight of systems, controls and governance arrangements. This is common in sectors such as charities, education bodies and public organisations, where formal accountability structures are in place.

They examine both financial and non financial areas, including risk management, compliance requirements and operational processes. Audits are usually planned in advance with the organisation, followed by fieldwork and a structured report outlining findings. Depending on the client, results may also be presented to boards or committees responsible for governance.

Key Highlights:

• Chartered accountancy and advisory firm
• Internal audit across financial and operational areas
• Experience with public sector and not for profit bodies
• Structured audit methodology
• Can work remotely or on site
• Part of a wider assurance offering

Services:

• Internal audit reviews
• Risk management assessments
• Governance evaluations
• Compliance reviews including GDPR
• Financial control testing
• External audit and advisory work

Contact Information:

• Website: www.pricebailey.co.uk
• Email: web.enquiry@pricebailey.co.uk
• Facebook: www.facebook.com/PriceBaileyLLP
• Twitter: x.com/price_bailey
• LinkedIn: www.linkedin.com/company/price-bailey
• Instagram: www.instagram.com/pbpeople
• Address: 14 David Mews, London, W1U 6EQ
• Phone: 020 7487 4870

9. Complyport 

Complyport is a London based consultancy focused on regulatory compliance for financial services firms. Given London’s role as a global financial centre, many organisations must meet strict oversight from authorities such as the FCA and PRA, and internal audit plays a central role in demonstrating that compliance. Their work is closely tied to governance, conduct requirements and financial crime prevention.

They conduct risk based reviews, compliance health checks and targeted investigations to assess whether firms are operating within regulatory expectations. Areas examined can include anti money laundering controls, operational resilience and internal governance arrangements. Findings are typically reported to senior management or boards to support oversight and decision making.

Key Highlights:

• Compliance consultancy specialising in financial services
• Based in the City of London
• Works with FCA and PRA regulated firms
• Internal audit aligned with regulatory frameworks
• Focus on financial crime prevention and governance
• Offers investigative and assurance work

Services:

• Risk based internal audits
• Compliance health checks
• AML and CTF assessments
• Systems and controls reviews
• Regulatory investigations
• Governance advisory

Contact Information:

• Website: complyport.com
• Email: info@complyport.co.uk
• Twitter: x.com/complyport
• LinkedIn: www.linkedin.com/company/complyport-ltd
• Address: 34 Lime Street, London, EC3M 7AT, United Kingdom
• Phone: +44 (0)20 7399 4980

10. Protiviti

Protiviti operates in London as part of a global consulting firm focused on risk, technology and internal audit. In a business environment where companies face rapid change – from digital transformation to new regulations – they support organisations that need a structured and forward looking audit function. Their work often connects internal audit with broader issues such as cybersecurity, data governance and operational resilience.

They provide a range of sourcing models, from fully outsourced internal audit functions to temporary support for existing teams. Reviews commonly include control testing, fraud risk analysis and assessments of complex programmes or technology environments. Because many large organisations in London operate across multiple jurisdictions, their approach often combines industry expertise with technical specialists who can address specific risk areas.

Key Highlights:

• Global consulting firm with London presence
• Focus on risk, technology and governance
• Internal audit delivered through flexible sourcing models
• Experience with complex and multinational organisations
• Strong emphasis on digital and emerging risks
• Uses data and technology in audit processes

Services:

• Risk based internal audits
• Technology and IT risk audits
• Controls advisory and testing
• Fraud risk management
• SOX compliance support
• Internal audit outsourcing or staff augmentation

Contact Information:

• Website: www.protiviti.com
• Facebook: www.facebook.com/Protiviti
• Twitter: x.com/ProtivitiUK
• LinkedIn: www.linkedin.com/company/protiviti-uk-
• Instagram: www.instagram.com/protiviti.uk
• Address: The Shard, 32 London Bridge Street, London, SE1 9SG, United Kingdom
• Phone: +44.20.7930.8808

11. PKF Littlejohn

PKF Littlejohn is a London headquartered firm that provides audit, tax and advisory services as part of an international network. Their internal audit work is typically aimed at listed companies, private groups and regulated businesses that need independent assurance over governance and controls. In London’s corporate landscape, this often includes financial services firms and organisations with complex reporting structures.

They offer both outsourced and co sourced internal audit arrangements, depending on whether a client has its own audit team. In some cases, they help establish an internal audit function from the ground up, while in others they provide specialist input or targeted reviews of specific risk areas. Training and support for boards or audit committees can also form part of their involvement.

Key Highlights:

• London based firm within a global network
• Experience with listed and regulated organisations
• Provides outsourced and co sourced audit models
• Supports development of internal audit functions
• Works alongside in house audit teams
• Offers training for management and boards

Services:

• Outsourced internal audit
• Co sourced internal audit support
• Control assurance reviews
• Internal audit training
• Advisory to Heads of Internal Audit
• Governance and risk reviews

Contact Information:

• Website: www.pkf-l.com
• Email: akonieczko@pkf-l.com
• Twitter: x.com/PKF_Littlejohn
• LinkedIn: www.linkedin.com/company/littlejohn
• Instagram: www.instagram.com/pkf.littlejohn
• Address: 15 Westferry Circus, Canary Wharf, London E14 4HD
• Phone: +44 (0)20 7516 2200

12. Windsor Audit

Windsor Audit is a UK auditing company with offices in London, primarily focused on statutory audit work for companies that require independent financial review. Although statutory audits differ from internal audits, their work often includes examining internal controls and identifying weaknesses in financial processes. For growing businesses or those seeking investment, this type of review can provide additional assurance about financial reliability.

Their audits involve detailed examination of records, transactions and supporting documentation to confirm that financial statements reflect the company’s position accurately. Where controls appear insufficient, recommendations may be provided to reduce risk and improve processes. They are registered with the ICAEW to carry out audit work in the UK.

Key Highlights:

• London based statutory audit firm
• Registered auditors authorised by ICAEW
• Focus on financial accuracy and compliance
• Reviews internal controls as part of audit work
• Works with companies subject to audit requirements
• Supports voluntary audits for growing businesses

Services:

• Statutory audits
• Financial statement verification
• Internal control assessment
• Compliance reviews
• Audit preparation guidance
• Risk related recommendations

Contact Information:

• Website: www.windsoraudit.com
• Email: mail@windsoraudit.com 
• Facebook: www.facebook.com/windsoraudit
• Address: 65 Compton Street London, EC1V 0BN
• Phone: +44 (0) 20 7183 9351

13. Azets

Azets provides audit and assurance services across the UK, including support for organisations operating in London’s competitive business environment. Their internal audit work is part of a broader assurance offering that aims to give stakeholders confidence in financial reporting and operational processes. Many mid market companies and public sector bodies rely on such reviews to demonstrate accountability.

They combine local knowledge with resources from a larger national organisation, which can be useful for businesses operating across different regions. Internal audits typically examine risks, controls and opportunities for improvement, with the goal of helping organisations understand how their systems perform and where adjustments may be needed. Engagements are designed to minimise disruption to day to day operations.

Key Highlights:

• National audit and advisory firm with London presence
• Serves private sector and public organisations
• Combines local teams with broader expertise
• Focus on reliable financial and operational assurance
• Reviews risks and improvement opportunities
• Part of wider audit and accounting services

Services:

• Internal audit reviews
• External statutory audits
• Assurance and compliance support
• Risk assessments
• Financial reporting assurance
• Advisory services

Contact Information:

• Website: www.azets.com
• Email: info@azets.co.uk
• LinkedIn: www.linkedin.com/company/azets
• Instagram: www.instagram.com/azets_uk
• Address: 2nd Floor, Regis House, 45 King William Street, London

14. Kreston Reeves

Kreston Reeves is an accountancy and advisory firm with offices in London and the South East, operating within an international network. Their internal audit services are used by a wide range of organisations, including corporates, public sector bodies and not for profit groups. In London, where many organisations must demonstrate accountability to regulators and stakeholders, independent reviews of governance and operations are often essential.

They carry out operational, financial and technology related audits, looking at how controls function and whether risks are properly managed. Services can be delivered as a complete outsourced internal audit function or alongside an existing team. Their work may also include due diligence reviews, fraud assessments and industry specific audits tailored to regulatory requirements.

Key Highlights:

• Accountancy firm with international network support
• Internal audit across multiple sectors
• Works with public sector and not for profit organisations
• Offers outsourcing or co sourcing arrangements
• Covers operational, financial and technology risks
• Members of professional audit bodies

Services:

• Internal operational audits
• Governance and compliance reviews
• Technology and cyber risk audits
• Fraud risk assessments
• Due diligence reviews
• Internal audit advisory

Contact Information:

• Website: www.krestonreeves.com
• Twitter: x.com/KrestonReeves
• LinkedIn: www.linkedin.com/company/kreston-reeves
• Address: 2nd Floor, 168 Shoreditch High Street, London, E1 6RA
• Phone: +44 (0)330 124 1399

15. Wem & Co

Wem & Co is a chartered accountancy firm based in West London that provides audit services to businesses and organisations across various sectors. Their internal audit and risk management work is part of a broader offering that includes statutory audits and specialist assurance assignments. In a city with diverse industries, they often deal with companies needing both regulatory compliance and practical financial oversight.

Their audit work can cover financial reporting, due diligence and risk evaluation, as well as sector specific assignments such as charity or pension scheme audits. Internal reviews are typically designed to give management a clearer understanding of financial health and control effectiveness. They also undertake specialist reports for regulated activities where independent verification is required.

Key Highlights:

• West London chartered accountancy firm
• Provides internal audit and risk management support
• Experience across multiple sectors
• Conducts specialist assurance assignments
• Works with charities and regulated entities
• Offers both statutory and voluntary audits

Services:

• Internal audit and risk reviews
• Statutory audits
• Financial due diligence
• Forensic accounting services
• Regulatory reporting
• Specialist assurance engagements

Contact Information:

• Website: www.wem.biz
• Email: mail@wem.biz
• Facebook: www.facebook.com/WemAccountant
• Twitter: x.com/wemandco
• LinkedIn: www.linkedin.com/company/wemandco
• Address: Savoy House, Savoy Circus, London W3 7DA
• Phone: 020 8740 6000

16. RSM

RSM operates in London as part of a global network of audit, tax and consulting firms. Their internal audit services sit within a wider risk advisory practice, supporting organisations that want independent evaluation of their control environment and risk management processes. In a large business centre like London, companies often use external auditors to complement internal oversight structures.

They work with management to understand strategy and operational drivers, then assess whether controls and governance arrangements support those objectives. Where weaknesses are identified, they may assist with developing solutions or implementing improvements. Their work can also extend into areas such as fraud prevention, regulatory compliance and information systems assurance.

Key Highlights:

• Global network firm with London operations
• Internal audit integrated with risk advisory services
• Focus on governance and control effectiveness
• Supports strategic risk management
• Experience across industries
• Provides implementation support where needed

Services:

• Internal audit reviews
• Governance and compliance assessments
• Fraud prevention and investigation
• Information systems assurance
• Enterprise risk management support
• Regulatory advisory

Contact Information:

• Website: www.rsm.global
• Facebook: www.facebook.com/GlobalRSM
• Twitter: x.com/RSM_Global
• LinkedIn: www.linkedin.com/company/rsm-international-limited
• Address: 200 Aldersgate Street, London, EC1A 4HD

17. Evalian

Evalian provides ISO focused internal auditing and consultancy services across the UK, including organisations based in London that need to maintain certification standards. Their work centres on management systems such as quality, information security and business continuity, which many companies must demonstrate to clients or regulators.

They conduct audits on site or remotely, reviewing documentation, processes and compliance with ISO requirements. The outcome typically includes a formal report identifying nonconformities and areas for improvement. This type of internal audit is often used by organisations without dedicated in-house specialists or those preparing for certification or recertification assessments.

Key Highlights:

• Specialist provider of ISO internal audits
• Supports multiple ISO standards
• UK wide service including London organisations
• Onsite and remote audit options
• Suitable for single or multi site operations
• Provides structured audit reporting

Services:

• ISO internal audits
• Audit scoping and planning
• Compliance assessments
• Nonconformity identification
• Improvement recommendations
• Certification preparation support

Contact Information:

• Website: evalian.co.uk
• Email: hello@evalian.co.uk
• LinkedIn: www.linkedin.com/company/evalian
• Address:  Blackwell House, Guildhall Yard, London, EC2V 5AE
• Phone: 03330 500 111

Conclusion

London has no shortage of internal audit providers, but they do not all serve the same purpose or type of organisation. Some firms focus on large corporates and regulated sectors, others work closely with charities, public bodies or growing private companies, and a few specialise in technical areas like ISO systems or financial services compliance. The right choice usually depends less on reputation and more on fit – how well a firm understands your industry, your size, and the level of scrutiny you operate under.

For many organisations, internal audit is not about ticking a requirement but about getting a clearer view of what is actually happening inside the business. An external team can spot patterns, gaps or risks that internal staff may overlook simply because they are too close to day to day operations. Taking time to compare different London based firms, their focus areas and working styles can make the difference between a routine review and something genuinely useful.