Blog · 2026-04-03 · manager

Due Diligence Services in the UK: A Practical Companies Overview

If you’re navigating a merger, acquisition, or major investment in the UK, due diligence is the step that turns assumptions into solid facts. This guide walks you through the landscape of due diligence companies operating here, focusing on the core services they deliver: financial due diligence, commercial due diligence, tax due diligence, and vendor due diligence.

It’s not a ranking or endorsement – just a straightforward look at how these companies approach the work, the types of businesses they typically support (from mid-market deals to larger transactions), and what tends to set their capabilities apart.

Some offer a broad, integrated view across multiple due diligence types, while others focus tightly on one area for deeper insight. The aim is simple: give you clear context so you can weigh your options and find the right match for your specific situation.

Acumon

Acumon operates as a UK-based company with its main office in West London, it serves clients across the country. The company focuses on specialist advisory work, particularly in due diligence for M&A deals.

Its services connect closely to UK regulatory standards through registered audit status and a team of UK-qualified professionals. This setup supports businesses navigating transaction requirements in competitive markets. The emphasis stays on practical compliance and risk awareness during deals.

The due diligence process zeroes in on spotting weaknesses early in financials, commercial setup, tax positions, and overall readiness. It helps strengthen internal checks, builds greater confidence in the information shared, and highlights technology or operational risks that could affect the deal. This approach gives clearer visibility into potential issues before closing.

Key Highlights:

Registered audit firm with ICAEW authorisation
All professionals based in the UK
Specialised team for M&A due diligence
Expertise in commercial and financial risk assessment
Focus on actionable insights for transaction risks
Integration with broader M&A advisory needs

Services:

Commercial due diligence
Financial due diligence
Tax due diligence
Vendor due diligence

Contact Information:

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

Accounts and Legal

Accounts and Legal provides legal due diligence as part of business transactions in the UK. The company supports buyers and sellers during acquisitions, investments, or restructurings. It focuses on uncovering legal risks tied to contracts, compliance, intellectual property, and employment matters.

The service involves a thorough review once a deal outline is agreed. It identifies potential liabilities and compliance issues to give a clear picture of the business’s legal position. Early involvement helps spot hidden problems and suggests practical actions. This approach supports informed decisions and avoids surprises in deals. The company handles both buy-side and sell-side scenarios across various transaction types.

Key Highlights:

Specialised in legal due diligence
Focus on contracts and compliance risks
Support for acquisitions and investments
Emphasis on early risk identification
Practical recommendations for issues

Services:

Legal due diligence
Contract review and analysis
Compliance checks
Intellectual property assessment
Employment-related due diligence

Contact Information:

Website: accountsandlegal.co.uk
Phone: 0161 820 0200
Address: 81 King Street, Manchester, Greater Manchester, M2 4AH

AlixPartners

AlixPartners delivers mergers and acquisitions advisory with a strong emphasis on due diligence. The company works with buyers across industries to assess potential targets. It combines commercial, operational, and technology perspectives in its transaction support.

Outside-in due diligence uses AI-enabled tools for quick insights into targets. Commercial and operations due diligence examines growth potential, optimization opportunities, and value creation drivers. Technology due diligence evaluates readiness for change and digital risks. The fact-based approach provides clarity for deal theses and supports underwritable decisions. Services cover the full deal lifecycle with attention to protecting and driving value.

Key Highlights:

AI-enabled outside-in due diligence
Deep commercial and operations focus
Technology and digital risk assessment
Fact-based value creation insights
Support across industries and geographies

Services:

Outside-in due diligence
Commercial due diligence
Operations due diligence
Technology due diligence

Contact Information:

Website: www.alixpartners.com
Phone: +44 20 7098 7400
Email: mveldon@alixpartners.com
Address: 6 New Street Square, London, EC4A 3BF, United Kingdom
LinkedIn: www.linkedin.com/company/alixpartners
Instagram: www.instagram.com/alixpartnersllp

BDO (UK)

BDO (UK) offers transaction services including due diligence for various deal types in the UK market. The company supports mergers, acquisitions, investments, and capital raises. It works with corporates, private equity, and financial investors, often in mid-market contexts.

Due diligence covers financial aspects like earnings quality and cashflow, alongside commercial views on market position and growth plans. Operational reviews look at processes and performance, while IT and digital checks assess technology infrastructure. ESG factors get attention for sector-specific risks and opportunities. The process typically runs four to six weeks, identifying risks and value drivers. Buy-side and sell-side support helps manage risks and maximize deal outcomes.

Key Highlights:

Comprehensive transaction due diligence
Mid-market deal expertise
Financial and commercial analysis
Operational and IT reviews
ESG risk assessment
UK market focus including London Stock Exchange

Services:

Financial due diligence
Commercial due diligence
Operational due diligence
IT and digital due diligence
ESG due diligence
Tax due diligence (transaction-focused)
Post-transaction due diligence

Contact Information:

Website: www.bdo.co.uk
Phone: 0117 930 1500
Email: experienced.hire@bdo.co.uk
Address: Bridgewater House, Finzels Reach, Counterslip, Bristol, BS1 6BX, United Kingdom
LinkedIn: www.linkedin.com/company/bdo-llp
Instagram: www.instagram.com/bdo_uk

EY

EY provides mergers and acquisitions due diligence through its strategy and transactions team. The company handles buy-side and sell-side engagements across different transaction types. It integrates multiple perspectives to assess risks and opportunities in deals.

Services include financial due diligence on historicals and forecasts, commercial reviews of market positioning and growth, and operational checks on cost structure and model. Tax due diligence covers transaction implications, while IT, cyber, and product/technology assessments evaluate resilience and maturity. Human resources and sustainability reviews address exposures and peer comparisons. The hypothesis-driven, data-informed approach delivers actionable insights for decision-making and value creation.

Key Highlights:

Integrated multi-type due diligence
Data-driven and hypothesis-based
Focus on risks and value creation
Sector experience in assessments
Advanced analytics collaboration

Services:

Financial due diligence
Commercial due diligence
Operational due diligence
Tax due diligence
IT due diligence
Cyber due diligence
Sustainability due diligence

Contact Information:

Website: www.ey.com
Phone: +44 20 7951 2000
Address: 3rd Floor, Edward Pavilion, Royal Albert Dock, Liverpool L3 4AF
LinkedIn: www.linkedin.com/company/ernstandyoung
Facebook: www.facebook.com/pages/Ernst-Young/195665063800329
Twitter: x.com/EYnews

Harold Sharp

Harold Sharp provides financial due diligence services in the UK market. The company supports buyers and investors during acquisitions. It also handles vendor due diligence to help sellers prepare and present their business.

The approach involves detailed checks on assumptions and expectations in pending deals. Experts validate key aspects to give a clear view of the investment. This helps ensure the right business gets acquired at a fair price. The service focuses on major moves like buying a company or major project. It aims to provide proactive advice throughout the process.

Key Highlights:

Buy-side due diligence support
Vendor due diligence preparation
Financial validation focus
Detailed assumption checking
Advice for acquisitions

Services:

Vendor due diligence
Buy-side due diligence
Financial due diligence

Contact Information:

Website: www.haroldsharp.co.uk
Phone: 0161 905 1616
Email: intouch@haroldsharp.co.uk
Address: 5 Brooklands Place, Brooklands Road, Sale, M33 3SD
LinkedIn: uk.linkedin.com/company/harold-sharp
Twitter: x.com/Harold_Sharp
Instagram: www.instagram.com/haroldsharp.co.uk

Investec Advisory

Investec Advisory handles transaction support in mergers and acquisitions. The company works on international deals with due diligence integrated into the process. It addresses current M&A themes through advisory services.

Due diligence appears as part of broader deal execution and support. The focus stays on transaction-related insights rather than standalone due diligence pages. Services tie into helping clients navigate complex deals. This includes elements like vendor due diligence in sell-side contexts. The advisory covers key international themes affecting transactions.

Key Highlights:

M&A transaction support
Integration with deal themes
Vendor due diligence context
International deal focus
Advisory for complex transactions

Services:

Transaction advisory
Vendor due diligence support
M&A due diligence integration

Contact Information:

Website: www.investec.com
Phone: +44 (0)20 7597 4000
Email: online.queries@investec.co.uk
Address: 30 Gresham Street, EC2V 7QP, United Kingdom
LinkedIn: www.linkedin.com/company/investec
Facebook: www.facebook.com/InvestecBank
Twitter: x.com/Investec
Instagram: www.instagram.com/investec

Johnston Smillie

Johnston Smillie offers a due diligence service for business transactions in the UK. The company guides clients through buying, selling, or merging businesses. It helps ensure a complete understanding of commitments involved.

The process can involve full handling or step-by-step guidance. It covers financial elements like liabilities and value assessment. Commercial aspects include market conditions and funding options. This thorough review reduces risks and clarifies worth. Clients go into deals informed to avoid overpaying or undervaluing. The service aims for smooth completion of transactions.

Key Highlights:

Guidance through due diligence process
Risk reduction focus
Business value assessment
Market and funding review
Smooth transaction completion

Services:

General due diligence service
Financial due diligence aspects
Commercial due diligence elements

Contact Information:

Website: www.jsca.co.uk
Phone: 0131 317 7377
Email: mail@jsca.co.uk
Address: 5 South Gyle Crescent Lane, Edinburgh, EH12 9EG
LinkedIn: www.linkedin.com/company/johnston-smillie-ltd
Facebook: www.facebook.com/johnstonsmillie
Twitter: x.com/johnstonsmillie

MHA

MHA provides corporate finance services with due diligence in transaction contexts. The company supports acquisitions, disposals, and M&A activities. It delivers objective reviews to manage risks in deals.

Due diligence includes financial checks and tax implications for transactions. Vendor due diligence helps sellers prepare and mitigate issues. Reports offer succinct analysis with commercial recommendations. The approach validates assumptions across strategic and operational areas. Services extend to cross-border transactions when needed. This helps clients make informed decisions on risks and opportunities.

Key Highlights:

Objective due diligence delivery
Risk identification and mitigation
Vendor due diligence assistance
Cross-border transaction support
Succinct reporting

Services:

Tax due diligence
Financial due diligence
Vendor due diligence
Transaction due diligence support

Contact Information:

Website: www.mha.co.uk
Phone: +44 (0)131 225 4681
Address: 6 St Colme Street, Edinburgh EH3 6AD
LinkedIn: www.linkedin.com/company/mha-uk
Facebook: www.facebook.com/people/MHA-Accountants/100063452388108
Instagram: www.instagram.com/mhaaccountants

ONEtoONE Corporate Finance

ONEtoONE Corporate Finance specializes in M&A advisory with due diligence support integrated into buy-side and sell-side processes. The company coordinates aspects of due diligence during transactions. It handles sell-side preparation and buy-side target assessments across various sectors.

Due diligence coordination covers financial, legal, tax, operational, and cultural elements in mergers. The process includes managing virtual data rooms for auditors. Support extends to negotiations and closing stages. This helps identify and mitigate risks throughout the deal. The advisory focuses on maximizing value in sales and acquisitions.

Key Highlights:

Due diligence coordination in M&A
Virtual data room management
Buy-side and sell-side support
Risk mitigation focus
Transaction negotiation assistance

Services:

Due diligence support
Sell-side advisory
Buy-side advisory
Valuation
Merger advisory

Contact Information:

Website: www.onetoonecf.com
Phone: +34 911 83 48 58
Email: info.gb@onetoonecf.com
Address: Tower 42, 25 Old Broad Street, London, United Kingdom
LinkedIn: www.linkedin.com/company/onetoone-corporate-finance
Facebook: www.facebook.com/onetooneglobal

Opus Strategic Advisors

Opus Strategic Advisors delivers M&A advisory with end-to-end transaction support. The company assists in buy-side acquisitions and sell-side sales. It blends experience to handle growth-stage deals.

Buy-side services include discreet target contact and offer structuring. Due diligence coordination occurs alongside negotiations with advisors. Sell-side work focuses on presenting businesses to buyers. The approach covers strategic sourcing to post-deal integration. This provides comprehensive guidance through the transactional journey.

Key Highlights:

End-to-end M&A support
Discreet buy-side approach
Due diligence coordination
Strategic buyer access
Post-deal integration guidance

Services:

Buy-side advisory
Sell-side advisory
Due diligence coordination
Debt advisory
Growth and fundraising

Contact Information:

Website: opusllp.com
Phone: +44 (0) 121 222 4140
Email: birminghamenquiry@opusllp.com
Address: Cornwall Buildings, 45 Newhall Street, Birmingham, B3 3QR, United Kingdom
LinkedIn: www.linkedin.com/company/opus-advisory-group-uk
Facebook: www.facebook.com/opusbusinessadvisorygroup
Twitter: x.com/opus_llp

PKF Littlejohn

PKF Littlejohn offers transaction advisory including various due diligence types. The company supports mergers, acquisitions, and refinancings. It works with leadership teams on deal strategies.

Due diligence covers financial, tax, IT, ESG, regulatory finance, and actuarial areas. The process identifies risks for buyers and sellers. Hands-on involvement provides ongoing insights. Reports help address issues promptly. Services aim to maximize transaction value through informed decisions.

Key Highlights:

Multi-type due diligence
Transaction advisory integration
Risk identification focus
Hands-on senior involvement
ESG and IT coverage

Services:

Financial due diligence
Tax due diligence
IT due diligence
ESG due diligence
Regulatory finance due diligence
Actuarial due diligence

Contact Information:

Website: www.pkf-l.com
Phone: 01174039800
Email: contact@pkf-francisclark.co.uk
Address: 90 Victoria Street Bristol BS1 6DP
LinkedIn: www.linkedin.com/company/littlejohn
Twitter: x.com/PKF_Littlejohn
Instagram: www.instagram.com/pkf.littlejohn

PKF Smith Cooper

PKF Smith Cooper handles corporate finance with due diligence in deal processes. The company supports buy-side and sell-side transactions. It tailors services to client objectives.

Buy-side due diligence examines historical performance and forecasts. Vendor due diligence prepares reports for multiple acquirers. Tax due diligence addresses transaction implications. Wider support includes valuation and financial modelling. This helps drive competitive processes and robust offers.

Key Highlights:

Tailored buy-side due diligence
Vendor due diligence reports
Transaction-specific scopes
Valuation and modelling support
Competitive bid facilitation

Services:

Vendor due diligence
Buy-side due diligence
Financial due diligence
Tax due diligence
Valuation

Contact Information:

Website: www.pkfsmithcooper.com
Phone: 0121 236 6789
Email: careers@pkfsmithcooper.com
Address: 2 Cornwall Street, Birmingham, B3 2DX
LinkedIn: www.linkedin.com/company/pkfsmithcooper
Facebook: www.facebook.com/PKFsmithcooper
Twitter: x.com/PKFSmithCooper
Instagram: www.instagram.com/pkfsmithcooper

Saffery

Saffery offers transaction services with a focus on financial due diligence in the UK. The company supports clients through deal processes in acquisitions and investments. It provides tailored analysis of financial performance and position.

Financial due diligence involves thorough reviews of profitability, risks, and opportunities. Tax due diligence uncovers historical exposures and compliance issues. Vendor due diligence identifies financial, operational, and tax risks that could affect buyer views or pricing. The team conducts detailed risk assessments across financial, operational, and market areas. This helps mitigate issues and supports smoother transactions. Services extend to buy-side and sell-side contexts in various sectors.

Key Highlights:

Financial due diligence analysis
Tax due diligence exposures
Vendor due diligence risks
Risk assessment coverage
Buy-side and sell-side support
Tailored transaction insights

Services:

Vendor due diligence
Financial due diligence
Tax due diligence

Contact Information:

Website: www.saffery.com
Phone: +44 (0)330 094 3384
Email: info@saffery.com
Address: St Catherine’s Court, Berkeley Place, Clifton, Bristol BS8 1BQ, UK
LinkedIn: www.linkedin.com/company/saffery
Instagram: www.instagram.com/saffery_uk

Salhan Accountants

Salhan Accountants provides due diligence reviews for business acquisitions and mergers. The company works alongside legal advisers during investments. It draws on experience with various businesses to examine financial aspects.

The service covers past and projected financial performance. It looks at accounts, cash flow, asset valuations, and property matters. Tax compliance gets checked as part of the overall picture. This builds a complete view of the business’s financial health. Clients gain clarity before committing to a deal. The approach helps avoid unexpected issues in transactions.

Key Highlights:

Financial aspects review
Acquisition and merger focus
Past and future performance check
Asset and cash flow analysis
Tax compliance inclusion

Services:

Due diligence examination
Financial performance review
Asset valuation assessment

Contact Information:

Website: salhanaccountants.co.uk
Phone: 0121 455 7475
Email: enquiries@salhanaccountants.co.uk
Address: 3rd floor, 54 Hagley Road, Edgbaston, Birmingham B16 8PE

Steedman and Company

Steedman and Company includes due diligence in its accounting and management services. The company supports investigations into businesses for acquisition. It positions due diligence as a key step in evaluating targets.

The process involves conducting investigations into the business and its assets. This typically covers financial and operational elements for potential buyers. The service helps clarify what is being acquired. It supports voluntary reviews before deals proceed. This provides practical insights for decision-making in acquisitions.

Key Highlights:

Acquisition investigation focus
Business and asset review
Financial due diligence element
Management context support

Services:

Due diligence investigation
Financial due diligence
Management due diligence aspects

Contact Information:

Website: www.steedman.co.uk
Phone: 0191 271 0827
Address: 9 Beaumont House, Redburn Road, Westerhope, Newcastle-Upon-Tyne NE5 1NB
LinkedIn: www.linkedin.com/company/steedman-and-company-ltd-
Facebook: www.facebook.com/steedmanandcompany
Twitter: x.com/steedmancompany

Conclusion

The best choice of due diligence company often comes down to factors like the scale of your deal, the industry involved, how mature your internal processes are, and any specific regulatory demands in play.

Some companies bring an integrated perspective that covers several due diligence angles at once, while others deliver sharp, specialised focus on a single type.

This overview sets out the main players and their typical approaches without favouring any – the goal is to equip you with neutral context for comparing services and identifying a partner that fits.

Ultimately, the right partner delivers independent assurance and practical steps to reduce risks and support resilience.