About Us

Mercer Lewin was founded in 1983 by Martin Mercer and since 1 January 2008 has traded as a limited company. The directors and consultants have a wealth of both practice and industry experience. Our consultant Martin Mercer was the original founder and has grown its client base and services, mainly through personal recommendation.  We currently operate from an office in Central Oxford. From the beginning, we have been committed to providing a friendly, personal service to clients, a number of whom have been with the firm since its inception.  We are proud that we have a number of long-serving staff who have come to know many of our clients well and, in dealing with Mercer Lewin, clients can be confident of the attention of staff and directors who are familiar with their affairs.

Over the years we have had a number of major successes in taking companies to the market and in assisting owner-managers to achieve profitable sales of their businesses.  

Mercer Lewin is a leading member of Heads Together, an association of like-minded firms from across the UK who meet twice a year to discuss technical issues and share information. This gives us further capacity to be able to draw on the expertise of other member firms when necessary.

Andrew Churchill Stone - FCA DChAa (Director)

Andrew was born and grew up in Oxford and trained at another local firm where he became an audit manager. He joined Mercer Lewin in 1997 and became a partner in 2003. He works with a broad range of clients and has been awarded the ICAEW’s Diploma in Charity Accounting in recognition of his experience in the field. He is responsible for accounting and audit technical matters within Mercer Lewin and also leads the firm’s work advising flat management companies and parishes in the Church of England.

Andrew is married to Anne and they have five children. Outside work he can usually be found in the realm of performing arts, either as an actor, director or musician. He is a part-time organist and a school governor.

Jon Swayne - FCA  (Director)

Jon trained and qualified at a centrally based Oxfordshire firm where he became a manager. He spent several years in industry in senior and Finance Director roles in SME and International businesses in industries such as motor sport, retail, import/distribution, manufacturing/construction and software providers. He  joined Mercer Lewin with a view to partnering Andrew whom he has known for over 25 years and to assist Martins wish to spend more time with his family and interests.

Interests outside work include motor home travel, golf, skiing and outdoor activities. As a secondary school governor Jon aims to bring his knowledge to school finance committees and objectives.

Martin Mercer  - FCA  (Consultant)

Martin Mercer the original founder qualified with Binder Hamlyn in London and worked in the shipping and leisure industries. He then worked for the Ellerman Lines group for eight years as Finance Director of a number of group companies and latterly as Finance and Development Director of The Belfry hotel and golf complex, and was subsequently Finance Director of a travel group. before setting up Mercer Lewin in Oxford in 1983. He is married with three daughters and has recently moved to Charlbury. He is a Life Member of MCC and enjoys all sport, music and the theatre.  Active participation is now focused on real tennis, golf and bridge.

Caroline Brown - Personal Tax Manager ATT

Initially a senior tax officer with HM Revenue & Customs and then a personal tax specialist with a national accountancy firm, Caroline moved to Mercer Lewin in 1988 in order to work with a more diverse range of clients, where she could offer a focused service and utilise all of her skills.

She enjoys the variety and in-depth knowledge required to be part of a small team where everyone has an important role to play.

In her spare time Caroline enjoys travel and socialising. She loves sport, is a keen skier.


Julia McMillan  MAAT  - Accounts Manager

Julia started working for Mercer Lewin in 1989. She subsequently qualified as an Accounts and Tax Technician. She looks after many of our management accounting assignments as well as preparing annual accounts for sole traders, partnerships and companies.

“I enjoy working for a small practice and the diverse range of activities of our clients’ businesses”.

As a mother of a young daughter, time away from work is spent enjoying family life and socialising with friends.


Joanne Alistoun BSc (Hons) ACA - Audit and Accounts Manager

Joanne graduated in Mathematics at Exeter University before working for a large accountancy firm in Devon where she qualified as a Chartered Accountant. She relocated to Oxford in 2008 to join her partner and has worked for Mercer Lewin since.

She is involved in the statutory audit of a variety of companies and charities and prepares accounts and tax returns for a wide range of businesses, including sole traders, partnerships and LLPs.

In her spare time she enjoys spending time with her family. She has recently returned from maternity leave following the arrival of a daughter.


Gale Campbell - Personal Tax

Gale joined the firm in October 2017 and is a member of the Association of Tax Technicians (ATT) and Association of Chartered Certified Accountants (ACCA). After a spell in accounting she favoured personal tax work and has been involved in this area for over 10 years. She has gained extensive experience in assisting clients with their tax compliance and advising on potential areas of change and considers providing a high quality service to the clients with whom she deals a priority.

Gale lives in Oxford with her husband and three children, who we understand keep her very busy! In her spare time she enjoys swimming , cycling and travelling.

Satya Maheshwari - Payroll Supervisor

Satya is a qualified Chartered Accountant from India, He has diverse experience of accounts and payroll. He joined our firm in the Summer of 2017 and is currently responsible for payroll and related work for a wide range of our clients dealing with queries and liaising with HMRC to resolve any issues they have. He is also responsible for handing Auto Enrolment compliance.

He is married and has a daughter and in his spare time enjoys travelling and exploring different countries. He has a keen interest in politics and current affairs.

Tasdik Mahmud - Accountant

Tasdik has a bachelor's degree in Accounting and Finance from Warwick University and a master's degree in Accounting from the London School of Economics. He trained as an audit associate with a Deloitte associated firm in Bangladesh as well as a spell working at Grant Thornton Consulting. He is a CIMA finalist awaiting possible future membership.

He relocated to Oxford in 2017 with his wife who is a student at Oxford University and joined Mercer Lewin at the end of that year.

Currently he is involved in Financial accounts preparation for companies and sole traders and  as well as being part of the Audit team.

In his spare time he reads books of every genre, watching and playing football as well as socialising with friends and family.

Luke Barter - Trainee Accountant

Luke is our trainee accountant and is studying towards his AAT level 4 qualification. He is involved with the preparation of accounts for a wide variety of companies and sole traders, and in carrying out audit work.

"I enjoy working for Mercer Lewin as it allows me to gain experience with a wide variety of clients and in a large range of accountancy work”

In his spare time he likes to play and watch football as well as socialising with friends and family.

Helen Hardaker - Practice Secretary

Since gaining secretarial qualifications Helen has worked in a variety of organisations, including Cambridge and Oxford Universities.  She has worked at Mercer Lewin since 1997 and enjoys the variety of the job, especially meeting our clients both existing and new.

In her spare time Helen enjoys travelling, cinema, baking, reading, socialising with friends and, most of all, seeing her grand-daughter regularly.