The Partners

We offer a wide and diverse wealth of experience within the Sunningdale practice near Ascot Berkshire, which is also reflected in the width and diversity of our client portfolio from owner managed businesses and private clients to professional practices and large international groups.

With 60 years’ expertise in UK and international markets we offer clients dependable and best advice throughout their business and personal financial lives.

We are genuinely client focused and put the needs of our clients first. Ongoing appraisals ensure we offer advice and assistance when it’s required.

Dawn O'Leary

For audit & assurance, accountancy and international business services
Graduated from Dundee University with an MA (Hons) in Accountancy and qualified as a Chartered Accountant in 1992 with a top 50 firm in Scotland before moving south. Dawn has been with Davis Burton Sellek since, was admitted as a partner in 1998 and is now the firm's Managing Partner.

Dawn has developed a mixed and diverse client portfolio comprising small, medium and large companies in market areas including construction, shipping, recruitment and property. Her local client base covers Sunningdale, Ascot, Bracknell, Virginia Water, Woking, Camberley among others. She also has a number of national and international clients including Dutch, Hungarian, Austrian, Czechoslovakian, Turkish, Indian, American and Far Eastern. One specific area of expertise is advising UK and European companies operating on large UK projects.

Responsible for audit, accountancy and business services, Dawn ensures that all clients have a dedicated manager and team suited to their specific requirements. She is passionate about the role which small to medium sized businesses play in today's market and how the accountancy profession can best serve their needs. She currently sits on the General Practitioners Committee of the Institute of Chartered Accountants of Scotland (ICAS) representing members in England and Wales.

In her spare hours Dawn devotes her time to her two sons and most weekends is usually found cheering on from the side of a football pitch.

Mark Busby

Having been trained by the Inland Revenue and after serving with them for five years Mark moved into private practice where he obtained his professional qualifications and became a member of The Association of Taxation Technicians. He was admitted as Tax Partner in 2010.

With over 20 years' experience he advises on both business and personal tax matters, specialising in international tax issues, complex high net worth tax advice and wealth planning. His enviable reputation in the local and international arena extends to representing clients across a range of sectors including Trusts, Lloyds Underwriters and Non UK domiciliaries. His experience in advising on personal and corporate taxation extends across the US, South African, European, Indian and Turkish markets.

As the firm’s Tax Partner Mark aims to provide a “Boutique" service tailored around individual needs and believes strongly that good tax advice comes from getting to know clients, their backgrounds and the issues that affect their lives before even discussing the numbers.

Outside of the office Mark enjoys spending time with his family and plays guitar.

Colin Willett
Associate and Head of Audit & Business Services

For audit & assurance and accountancy services for owner managed businesses
It was always my ambition to have a career in either the accountancy or banking world. With this in mind, I headed to college to further my education and two years later left with a business studies diploma. It was shortly after leaving college in 1980 that I joined Davis Burton Sellek and soon after, became Treasurer of a local club. Colin was admitted as Associate in 2010.

As Associate and Head of Audit & Business Services, I am responsible for providing mainly auditing and accountancy services for the majority of UK-based clients, ably assisted by my accounts team. Our business client base is a wide and varied one, ranging from Opticians to Hypnotherapists and Actors to Musicians.

Outside of the office, my spare time is usually taken up travelling the country supporting Aldershot FC. During the summer months my free time may be spent visiting air shows, being an aviation enthusiast.