Audit and Assurance Companies in London: Practical Services Overview (2026)
AC
Acumon Chartered Accountants·13 min read
This practical guide looks at companies providing audit and assurance services in London, rather than ranking them from first to last. The selection covers different types of companies, from large organisations with broad audit, risk and assurance capabilities to more focused specialists serving particular sectors or client groups. Each profile gives context on the company, the organisations it works with, its relevant services and areas of strength. The aim is to make the differences easier to understand and help readers identify companies that fit their reporting, regulatory and assurance requirements.
Acumon
Acumon is a London-based firm of chartered accountants and registered auditors providing audit and assurance services to private companies, corporate groups, charities, regulated organisations, and Public Interest Entities. Its audit practice covers statutory and external audit alongside specialist assurance assignments for organisations with different reporting and regulatory requirements.
The firm works with organisations ranging from owner-managed businesses and companies approaching their first statutory audit through to international groups and London-listed entities. Acumon states that its audit practice serves organisations with UK turnover from £1 million to £500 million, with engagements supported by senior-led teams and digital audit processes.
Acumon is registered to carry out audit work by the ICAEW and is authorised by the Financial Reporting Council to undertake Public Interest Entity audits. This enables the company to work with listed and other public interest organisations that are subject to enhanced audit requirements, as well as businesses requiring standard statutory audit services.
Alongside financial statement audit, Acumon’s assurance work extends into areas such as internal audit, governance, risk, technology, ESG reporting, regulatory compliance, and controls. These services can be relevant where boards, management teams, investors, lenders, or regulators require independent examination of information beyond the annual financial statements.
International groups can also use Acumon for audit work involving UK subsidiaries and entities in other jurisdictions. The company holds Recognised Auditor status in Jersey and the Isle of Man and provides group audit services covering consolidation, component audit coordination, and multi-jurisdictional reporting requirements.
Acumon’s London audit and assurance offering therefore covers both recurring statutory obligations and more targeted assurance requirements. Engagements can address financial reporting and regulatory compliance while also identifying matters involving controls, governance, risk management, and the reliability of information used by stakeholders.
Audit and Assurance Capabilities
Acumon provides audit and assurance services across a range of organisational structures, regulatory environments, and reporting requirements.
These include:
Statutory and external audits for UK companies
Public Interest Entity (PIE) and listed company audits
Group and subsidiary audits for international structures
Charity and not-for-profit audits
Regulatory and specialist assurance engagements
Risk, governance, controls, and technology assurance
Audit and assurance engagements can be structured around statutory reporting obligations or a defined area where management, boards, regulators, investors, or other stakeholders require independent assurance. Acumon’s broader service offering also allows financial audit work to sit alongside relevant risk, technology, and governance reviews.
Regulatory Licences and Registrations
Acumon holds audit registrations and authorisations that support work with UK organisations and certain multi-jurisdictional groups.
These include:
ICAEW registered audit practice
FRC authorisation for Public Interest Entity audits
Jersey Recognised Auditor status
Isle of Man Recognised Auditor status
FCA exempt professional firm status
UK statutory audit registration
These registrations allow Acumon to undertake statutory and specialist audit work for organisations with different regulatory profiles, including private companies, listed entities, regulated businesses, charities, and groups containing entities in the UK, Jersey, and the Isle of Man.
Core Services
In addition to standard financial statement audits, Acumon provides audit and assurance services covering specialist regulatory, operational, and reporting requirements.
These include:
Statutory and external audit
Group and component audits
Public Interest Entity (PIE) audits
CASS and financial services audits
Charity and pension scheme audits
ESG and sustainability assurance
Internal audit, governance, and risk assurance
The appropriate scope depends on the organisation and the reason assurance is required. A growing private company may need its first statutory audit, while a regulated business may require both financial statement audit and additional reporting over client assets, controls, or compliance.
International organisations can face a different set of requirements. UK subsidiaries may need local statutory audits alongside reporting to an overseas parent, while groups operating across several jurisdictions may require coordinated component work, consolidation testing, and communication between audit teams.
Acumon works with organisations that are:
Approaching or exceeding statutory audit thresholds
Preparing for investment or other stakeholder scrutiny
Operating within regulated sectors
Managing UK and international group structures
Assurance requirements can also arise outside the annual statutory audit cycle. Independent reviews of ESG disclosures, governance arrangements, internal controls, technology risks, or other specified information can provide additional evidence where boards and external stakeholders need greater confidence in reported information or organisational processes.
Address: 1-2 Craven Road, Ealing, London, W5 2UA, UK
Deloitte
Deloitte’s UK Audit and Assurance practice covers external financial statement audits and wider assurance activities. Its external audit work provides independent opinions on financial statements and considers compliance with the relevant financial reporting framework.
The practice combines financial audit specialists with IT, data and analytics capabilities. Deloitte also provides broader assurance work and related advisory assignments, making it relevant to organisations with complex reporting environments or technology-dependent financial processes.
Key Facts
Ideal for: Large companies and organisations with complex financial reporting requirements
Core services: External audit, IT audit support, data analytics and assurance
Specialization: Large and complex audit and assurance engagements
Location: London and other UK locations
Notable strength: Integration of financial audit with technology, data and analytics capabilities
Contact Information
Website: www.deloitte.com
Phone: +44 (0)20 7936 3000
Address: 1 New Street Square London, EC4A 3HQ United Kingdom
LinkedIn: www.linkedin.com/company/deloitte
Facebook: www.facebook.com/deloitteuk
Twitter: x.com/deloitteuk
EY
EY’s UK Assurance practice combines audit with several related assurance disciplines. Its published capabilities include Audit, Climate Change and Sustainability Services, Financial Accounting Advisory Services, Forensic and Integrity Services, and Technology Risk.
Its audit teams use a globally connected methodology and technology platform, with continuing investment in analytics and AI-supported audit processes. The breadth of the assurance practice makes EY particularly relevant where financial reporting needs intersect with technology, sustainability or accounting advisory requirements.
Key Facts
Ideal for: Large, international and complex organisations
PwC’s audit practice focuses on independent financial statement audit and related assurance. Its audit work centres on assessing whether financial reporting presents a true and fair view and is free from material misstatement.
Beyond financial audits, PwC provides non-financial assurance for areas where organisations or regulators require independent scrutiny. Published examples include assurance over client assets and money, benchmarks and indices, and safeguarding arrangements for payment and electronic money institutions.
Key Facts
Ideal for: Large companies, regulated organisations and businesses requiring financial or non-financial assurance
Core services: Audit, non-financial assurance and capital markets assurance
Specialization: Financial reporting and regulated assurance
Location: London and other UK locations
Notable strength: Combination of financial audit and specialist non-financial assurance
Address: 1 Embankment Place London WC2N 6RH United Kingdom
LinkedIn: www.linkedin.com/company/pwc-uk
Facebook: www.facebook.com/PwCUK
Instagram: www.instagram.com/pwc_uk
KPMG
KPMG provides independent audit services designed to give investors and other stakeholders assurance over financial information. Its UK audit approach places emphasis on professional scepticism, independence, ethics and the use of data and analytics.
The firm is particularly relevant to organisations dealing with substantial reporting requirements, multiple stakeholder groups and complex financial data. Technology and analytics are incorporated into the audit process to help auditors identify areas requiring greater scrutiny.
Key Facts
Ideal for: Large and complex organisations
Core services: Financial statement audit and related audit services
Specialization: Data-supported audit and financial reporting assurance
Location: London and other UK offices
Notable strength: Investment in audit data and analytics technology
BDO provides external audits and a wider range of assurance services through its UK practice. Its published capabilities cover external audit, financial reporting, governance, risk and compliance, internal audit and risk assurance, as well as reporting under UK GAAP, IFRS and other international frameworks.
Its London office at Baker Street works with entrepreneurial mid-market businesses, listed companies, not-for-profit organisations and international businesses. This gives BDO a broad position between the largest multinational audit networks and smaller independent firms.
Key Facts
Ideal for: Mid-market, listed, international and not-for-profit organisations
Specialization: Mid-market and international audit
Location: 55 Baker Street, London
Notable strength: Broad financial reporting and risk assurance capabilities
Contact Information
Website: www.bdo.co.uk
Phone: 020 7486 5888
Address: 55 Baker Street London, W1U 7EU, United Kingdom
LinkedIn: www.linkedin.com/company/bdo-llp
Instagram: www.instagram.com/bdo_uk
Grant Thornton
Grant Thornton’s audit and assurance practice works with privately owned, private equity-backed, listed and mid-market organisations. Its external audit coverage spans commercial businesses, financial services, pensions, not-for-profit organisations and the public sector.
The firm’s wider assurance services extend beyond statutory financial statement audits. Published capabilities include ESG assurance, royalty and intellectual property audits, grant assurance, public sector value-for-money assurance and CASS assurance. International engagements are supported through its global network and common audit methodology.
Key Facts
Ideal for: Mid-market, PE-backed, listed and international organisations
Core services: External audit, ESG assurance, grant assurance, CASS assurance and other targeted reviews
Specialization: External audit and wider assurance
Location: London and other UK offices
Notable strength: Range of statutory and non-statutory assurance assignments
PKF Littlejohn provides audit and assurance services from offices including London, Leeds and Manchester. Its statutory audit practice works with listed and privately owned companies, UK and international groups and Public Interest Entities.
The assurance practice also covers governance, risk and control. PKF Littlejohn undertakes specialist limited assurance work for smaller local government authorities, while its broader corporate practice addresses internal controls, governance and risk management alongside financial audit.
Key Facts
Ideal for: Listed businesses, private companies, international groups and organisations needing specialist assurance
Core services: Statutory audit, governance, risk, controls and limited assurance
Specialization: Corporate and regulated audit and assurance
Location: London, Leeds and Manchester
Notable strength: Experience with listed companies, PIEs and international audits
Moore Kingston Smith provides corporate audit and financial reporting services to family-owned, privately held, listed, private equity-backed and public interest organisations. Its audit expertise covers UK GAAP, IFRS and US GAAP reporting environments.
The firm’s published services include audit, financial reporting, nonprofit reporting and royalty audits. As a member of Moore Global, it can also draw on an international network for organisations whose audit requirements cross jurisdictions.
Key Facts
Ideal for: Private, family-owned, listed, PE-backed and internationally active organisations
Forvis Mazars provides financial audit and independent assurance services to regional, national and international organisations. Its audit and assurance offering includes financial audit, corporate reporting, independent assurance and reviews, and related training services.
Its governance, risk and internal control practice adds internal audit, IT audit, governance reviews, risk management reviews, compliance reviews and assurance over outsourced service providers. The firm therefore covers both statutory financial audit and broader operational or controls-focused assurance requirements.
Key Facts
Ideal for: Regional, national and multinational organisations
Core services: Financial audit, corporate reporting, internal audit, IT audit and independent assurance
Specialization: Financial and broader organisational assurance
Location: London and multiple UK offices
Notable strength: Combination of financial audit with governance, risk and controls work
Contact Information
Website: www.forvismazars.com
Phone: +44 (0) 20 7063 4000
Address: 30 Old Bailey London EC4M 7AU United Kingdom
Saffery takes a partner-led approach to audit and assurance and adapts its work to the structure and requirements of individual organisations. Its core offering includes external audit, internal controls reviews and risk assurance.
External audit services cover statutory, non-statutory and special-purpose audits. The firm states that statutory assignments include AIM-listed companies, private companies, LLPs and qualifying charities, while its risk assurance practice supports commercial and not-for-profit organisations with risk identification, assessment, mitigation and reporting.
Address: 71 Queen Victoria Street, London EC4V 4BE, UK
LinkedIn: www.linkedin.com/company/saffery
Instagram: www.instagram.com/saffery_uk
Crowe
Crowe UK’s audit practice works with privately owned companies, private equity-backed businesses, public sector bodies, social purpose and not-for-profit organisations, and companies listed in the UK and internationally. Its statutory audit work is complemented by a separate range of assurance services.
Those assurance services include internal controls reports, independent examinations for smaller charities, third-party operations assurance, grant assurance and internal audit. Crowe also provides fully outsourced and co-sourced internal audit arrangements, governance reviews and specialist technology risk assurance.
Key Facts
Ideal for: Private businesses, listed companies, public sector and not-for-profit organisations
HaysMac operates a substantial London audit practice working with clients from Public Interest Entities to charities. Its client base includes listed companies across the Main Market, AIM and Aquis. HaysMac combines sector-specific audit teams with a cloud-based audit platform using data analytics, AI and collaboration tools, giving it particular relevance for organisations seeking a London-focused alternative to the largest global firms.
Key Facts
Ideal for: Listed companies, PIEs, charities and organisations requiring a sizeable London audit team
Core services: Financial audit and assurance
Specialization: Sector-focused audit
Location: London
Notable strength: Large dedicated audit practice with listed-company experience
Blick Rothenberg’s audit, accounting and outsourcing practice serves business owners, international groups, family businesses, privately owned companies and private equity-backed organisations. Its audit approach is designed around the risks, ownership structure and reporting requirements of each entity.
The firm also undertakes tailored assurance assignments when contractual or commercial arrangements require independent reporting. Examples include grant funding agreements, loan covenant testing, intellectual property licensing arrangements and service charge accounts. Its financial services practice adds CASS reporting, fund audits and ISAE 3402 internal controls reports.
Key Facts
Ideal for: UK businesses, international groups, financial services firms and privately owned companies
Core services: Audit, tailored assurance, CASS reporting, fund audit and controls reporting
Specialization: Cross-border and commercial assurance assignments
Location: London
Notable strength: Tailored assurance for contractual and regulatory requirements
Contact Information
Website: www.blickrothenberg.com
Phone: +44 (0)20 7486 0111
Address: 16 Great Queen Street, Covent Garden, London, WC2B 5AH
Rayner Essex provides audit and assurance services through its London and Hertfordshire practice. Its work includes statutory audit, group audit, component audit, regulatory reporting, special reporting and assurance engagements.
For organisations that do not require the scope of a full statutory audit, the firm can agree targeted assurance procedures around specific areas. Examples identified by Rayner Essex include internal controls and IT systems, due diligence reporting and grant claims. Its group and component audit capabilities are also relevant to UK subsidiaries and international corporate structures.
Key Facts
Ideal for: Private companies, UK subsidiaries and groups seeking a mid-sized audit firm
Core services: Statutory audit, group audit, component audit, regulatory reporting and assurance reviews
Specialization: Corporate and group audit
Location: London and St Albans
Notable strength: Group and component audit experience for international structures
Address: Tavistock House South, Tavistock Square, London, WC1H 9LG
LinkedIn: www.linkedin.com/company/rayner-essex
Facebook: www.facebook.com/rayneressexllp
Twitter: x.com/rayneressexllp
Instagram: www.instagram.com/rayneressex
Conclusion
Audit and assurance services in London vary considerably in scale and scope. Some firms concentrate on large listed and multinational organisations, while others have a stronger focus on mid-market companies, charities, regulated businesses, international subsidiaries or specialist assurance assignments.
The appropriate firm depends on the type of assurance required, regulatory status, reporting framework, organisational complexity and the level of sector expertise needed. Comparing statutory audit capabilities alongside areas such as internal controls, risk assurance, CASS reporting, group audits and non-financial assurance can help narrow the options to firms that fit the organisation’s actual requirements.
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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