Financial Services Lawyers
We are a specialist financial services law firm based in London. The firm and its lawyers are ranked by Legal 500 and Chambers.
We share the depth and breadth of decades of experience working with the full range of financial services firms from the largest banks and asset managers to smaller fintechs, payments, and crypto firms.
As financial services is all we do, it is important that we do it very well. All work is undertaken by a senior specialist lawyer – ensuring excellence, efficiency and responsiveness.
Firms We Work With
We have experience of providing legal and regulatory services to a wide range of firms in the financial services sector.

Digital Financial Services
We are passionate about innovation in financial services and support many firms from household name trail blazers in payments, to smaller fintech start-ups.

Fund & Asset Management
We have extensive experience of advising on fund structuring and marketing; and compliance with AIF / CIS regimes. We act for a range of asset managers on regulatory compliance.

Banks & Building Societies
We work with many UK & overseas banks & building societies on treasury (incl. reg capital); transactional (incl. client and business transfers) and regulatory compliance matters.

Investment Firms
We work with a diverse range of investment firms including equity / CFD brokers; wealth managers; IFAs; and commodity traders. We have a deep understanding of related regulation, in particular, MiFID2 and MIFIDPRU.

Insurers
We have a range of experience in the insurance sector, including analysis as to whether arrangements constitute a contract of insurance; and product design and distribution arrangements.
Why Choose Our Law Firm?
As lawyers specialising solely in financial services, we provide:

A wealth of experience across
financial services
We draw on over 80 years of combined experience working with a wide range of financial services firms. This experience means that we can share practical solutions that we have seen work before as well as develop new legal approaches.
As financial services is all we do, it is important that we do it very well. We closely follow regulatory developments, sit on industry working groups, and are involved in responding to the FCA and the PRA on key regulatory consultation papers.

Trusted and accessible
advisors
We invest time to understand our clients' businesses, build lasting relationships and become trusted advisors.
It is also important to our clients that we are accessible – always available at the end of the phone - and that work is done by a specialist senior lawyer, not handed down to junior associates.

A different way
of charging
Unlike many law firms, we don’t just charge by the hour.
We provide you with a firm estimate of costs before work starts so there are no surprises.
Our clients tell us that we provide City law firm quality at the right price point.
Expert Financial Services Lawyers
We are a specialist team of expert financial services lawyers and advisors.
Brian McDonnell
Partner
Brian is recognised for providing practical advice to a wide range of financial services firms. He has over 20 years of experience, 12 years as a city law firm partner most recently as head of Financial Markets at Addleshaw Goddard. He is ranked by both Chambers and Legal 500 as a leading individual (Financial Services: Non-contentious Regulatory).
Brian McDonnell
Partner
Brian is recognised for providing practical advice to a wide range of financial services firms. He has over 20 years of experience, 12 years as a City law firm partner most recently as head of Financial Markets at Addleshaw Goddard. He is ranked by both Chambers and Legal 500 as a leading individual (Financial Services: Non-contentious Regulatory).
He has in-depth industry knowledge, and has spent time as regulatory counsel at the London Stock Exchange and on secondment to Bank of America Merrill Lynch as the lawyer responsible for supporting MiFID implementation.
Brian is vice-chair of the City of London Law Society Regulatory Law Committee. He sits on the Lexis Financial Services Consulting Editorial Board. He is the UK legal advisor to the Association of International Life Offices. He is the author of Thomson Reuter’s A Practitioner’s Guide to Inside Information (2nd edition).
David Ellis
Partner
David has over 20 years of experience providing legal services to financial services firms – 8 years as a partner at Addleshaw Goddard.
He has in-depth industry knowledge having worked for a period in-house (at Citigroup and Legg Mason) with a particular focus on asset management.
He is especially expert on regulatory capital, client money and derivative matters. David also has experience with documenting a wide range of financial services arrangements such as outsourcing; broker agreements; administration agreements; ISDAs and custody agreements.
Linkedin
Paul Estlin
Consultant
Paul is a financial services regulatory lawyer with over 20 years’ experience. He has a wealth of experience, combining a deep understanding and technical knowledge with a practical approach. He worked as a regulator at the Financial Services Authority and one of its predecessors, the Personal Investment Authority.
Simon Williams
Consultant
Simon is a highly experienced financial services regulatory and commercial lawyer specialising in the insurance sector, with over 25 years experience. He was previously General Counsel for a major insurance firm and before that a Chambers ranked City law firm partner. Simon is a business-focused lawyer with a proven track record of solving complex issues.
Testimonials
"He consistently provides clear, robust commercial advice"
"He is very practical and gets to the solution very quickly.""
'He has very good technical knowledge across the full regulatory spectrum.'"
Brian McDonnell ‘understands how the advice impacts business’"
Insights
View our latest law firm news and insights.
CRD6: Clock ticking for Non-EU Banks
Background From 11 January 2027, non-EU banks providing “core banking services” into EU Member States will face a fundamentally different regulatory landscape under CRD6 (Directive (EU) 2024/1619). For banks headquartered in Asia-Pacific and other third countries that have historically provided cross-border lending, trade finance and other banking services into the EU — often in reliance […]
Recognition for McDonnell Ellis from Legal 500 and Chambers Legal Directories 2026
Specialist financial services law firm, McDonnell Ellis, has been recognised by both the Legal 500 and Chambers & Partners this year. The Legal 500 said of the firm: “McDonnell Ellis is the only specialist financial services regulatory law firm in England & Wales. I have used the firm on many occasions to support clients with […]
Crypto Regulatory Perimeter Takes Shape
Background On April 29, 2025, HM Treasury released a draft Statutory Instrument (“Draft SI”) and an accompanying policy note (the “Policy Note”) detailing the UK’s upcoming regulatory framework for cryptoassets. The Draft SI will amend the UK Regulated Activities Order to create multiple new regulated activities for cryptoassets covering stablecoin issuance, exchange operation, custody and […]
Financial Services Lawyers FAQS
Listed below are some common questions and answers about our firm.
If you cannot find an answer to your question, then book a free consultation today.
We specialise in legal and regulatory services to financial services businesses, including:
- Banks / Building societies
- Fund & Asset managers
- Wealth managers
- Investment firms
- Brokers
- Pension providers
- Insurers
- Fintechs
- Crypto providers
We advise on the full range of regulatory and commercial legal matters affecting financial services businesses. For example, our work includes:
- how to interpret and apply FCA and PRA regulation;
- how to implement new law and regulation affecting financial services businesses;
- advising on new business models including crypto projects;
- advising payments / e-money firms;
- designing and drafting regulatory capital instruments;
- fund structuring and drafting fund documentation;
- drafting agreements for financial services businesses including: customer Ts&Cs; outsourcing agreements; investment management agreements; and AIFM agreements; and
- due diligence of financial services businesses.
We also provide wider regulatory services including FCA / PRA authorisation applications; crypto-exchange registrations; drafting compliance documents / manuals; and regulatory consulting.
Yes, we work with many businesses who seek advice on whether they require authorisation by the FCA or the PRA. We can often help firms identify exemptions from the need for authorisation or provide advice on how they can change their business model to avoid the need for authorisation. We also advise on whether arrangements may constitute a Collective Investment Scheme (and/or an Alternative Investment Fund) which would require an FCA authorised operator (and/or AIFM).
Yes, we can help you apply for FCA or PRA authorisation and/or to register your crypto-exchange with the FCA.
As the UK’s only specialist financial services regulatory law firm, we collaborate with many law firms which don’t have our specialist regulatory capability (or don’t have sufficient capability). We help such law firms provide legal services to their clients or support on the regulatory elements of corporate / funds transactions.
McDonnell Ellis was established in May 2020 by two experienced financial services partners who left City law firm Addleshaw Goddard LLP.
Unlike many law firms, we don’t just charge by the hour. We provide you with a firm estimate of costs before work starts so there are no surprises. Our clients tell us that we provide City law firm quality at the right price point.
We are based in London, United Kingdom.
No, but we have an international network of the some of the best financial services lawyers and regulatory specialists. Unlike international firms which are restricted to using their local office, we can choose to work with the best lawyer / specialist in a foreign jurisdiction.
Yes, we are registered with the Solicitors Regulation Authority. You can view our registration profile here.









