John works with prominent international family offices on a cross-border basis and deals with structuring for UK residents and resident non-domiciled families. He creates structures for active entrepreneurs to hold business interests and advises on issues relating to the interaction of family and business governance. John is frequently listed in many publications as a leading private client adviser to international families, and has won many awards for his work, most recently the Spears Tax and Trust Lawyer of the Year Award 2017.

John has a deep interest in tax and regulatory policy and represents the profession in these matters. He has held a variety of senior posts in STEP and is currently co-chair of its public policy committee. In this role, John has been responsible for liaising with national and supra national bodies on matters of tax policy affecting wealthy families, and has been consulted by the Organisation for Economic Co-operation and Development in respect of its initiative for high net worth individuals; he also attended a number of sessions of the Financial Action Task Force Consultative Forum, which seeks views from the private sector on its proposals and guidance to Member States. John co-authored the STEP practice note on the Common Reporting Standard and trusts. 

He has also been involved with the International Academy of Trust and Estate Lawyers, becoming an academician by invitation in 2007 and elected as vice-president for Europe in May 2014; the American College of Trust and Estate Council since 2011, when he was invited to become an international fellow in recognition of his significant cross-border practice; and the Institute for Family Business, where for many years John has been a member of the advisory council in the UK, providing input on a wide range of legal and tax policy matters.