Internal Audit Services Companies in London: Firms List
AC
Acumon Chartered Accountants·17 min read
Choosing an internal audit provider in London is more than a simple compliance task. For many organisations, internal audit helps strengthen governance, improve oversight and ensure that financial and operational controls work as expected.
London is home to a wide range of firms offering internal audit services, from large professional services networks to smaller specialist advisory practices. Each firm brings different experience, sector knowledge and approaches to risk and governance.
This guide highlights a selection of internal audit services companies operating in London. Rather than ranking providers, the aim is to provide useful context about these firms, the types of organisations they typically support and the services they offer.
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.
Acumon is a London-based firm of chartered accountants, auditors and advisors that provides internal audit services as part of a wider range of audit, risk, tax and advisory support. With offices in West London and clients across the UK and internationally, the firm works with organisations that require support with financial oversight, governance and regulatory compliance.
In London’s highly regulated business environment, internal audit is closely connected to broader risk management and financial governance. Acumon works with finance leaders, boards and audit committees to review control frameworks, strengthen oversight and ensure that key processes remain aligned with UK regulatory expectations.
Internal audit engagements form part of the firm’s broader risk and technology advisory offering. Reviews focus on how controls, systems and operational processes function in practice, helping organisations identify potential weaknesses, improve compliance and build greater confidence in their reporting and internal controls.
Key Highlights:
London-based firm serving UK and international clients
Registered audit practice authorised by professional regulators
Internal audit delivered as part of wider governance and risk advisory
UK-based team including professionals with HMRC and regulatory experience
Experience supporting corporates, charities and international subsidiaries
Integrated accounting, audit, tax and advisory capabilities
Address: 1-2 Craven Road, Ealing, London, W5 2UA, UK
Phone: 020 8567 3451
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.
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.
Address: Office Gold, Building 7, Floor 5, 566 Chiswick High Road, Chiswick Business Park, London, W4 5YG
Phone: 0203 818 9530
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
Address: Fitzrovia, 60 Tottenham Court Road, London, W1T 2EW
Phone: +44 207 871 0485
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
Address: Unit A3, Gateway Tower, 32 Western Gateway, London E16 1YL
Phone: 0203 4411 205
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
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.
Address: The Hamilton Centre, Suite 3, First Floor, Rodney Way, Chelmsford, Essex, CM1 3BY
Phone: 01268 758000
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
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
Address: 34 Lime Street, London, EC3M 7AT, United Kingdom
Phone: +44 (0)20 7399 4980
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
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
Address: 15 Westferry Circus, Canary Wharf, London E14 4HD
Phone: +44 (0)20 7516 2200
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
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
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
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
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.
London offers a wide range of internal audit providers, but they often serve different types of organisations and needs. Some firms work mainly with large corporations and regulated industries, while others focus on charities, public sector bodies or growing private businesses. There are also specialist providers that concentrate on areas such as ISO systems or financial services compliance.
When choosing an internal audit provider, organisations usually look beyond reputation alone. Factors such as sector experience, understanding of regulatory requirements, approach to risk and governance, and the ability to work closely with management teams often play an important role.
This guide is intended to provide helpful context rather than rank firms. By comparing different providers, their services and areas of expertise, organisations can better identify a firm that fits their size, industry and governance needs.
AC
Written by the Acumon team
Acumon is an ICAEW-registered firm of chartered accountants and registered auditors
based in London, with offices in Pitstone, Aylesbury and Bournemouth. Need advice on
anything covered here? Talk to us.
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