His special expertise includes the fields of UK and foreign trusts and estates, tax planning and trust and personal taxation. He also has wide experience in charity, property, securities, partnership, professional negligence and family provision matters.

Simon’s leading cases include:

IRC v Berrill (income tax), re Trafford (CTT), Sinclair v Lee (ICI demerger), Ingram v IRC (IHT and leases), Keene v Martin (company), X v A (trustees' indemnities), Public Trustee v Cooper (conflicts of interest) and Sieff v Fox (trustees' errors).

The Legal 500 2006 recommends him as one of the leading silks Private Client (Trusts and Probate) work and describes him as "effective, firm very clear" and "provides comprehensible advice". The Legal 500 2006 also recommends him as a leading silk for Charity law and mentions that he has the "ability to identify problems other lawyers have overlooked and then provide workable solutions".

The Chambers & Partners Guide to the UK Legal Profession 2007 describes him as "always impressive, always meticulous and excellent with clients." As well as "practical, strategic thinking and very full practice - he's an absolute star." The Guide also mentions that he was declared "bloody marvellous" by clients, who also noted his "thorough and high-powered" advocacy skills. One client dubbed him "extremely user-friendly and hard-working, with very sound judgment."

He is a member of the Chancery Bar Association, the Revenue Bar Association and the Society of Trust and Estate Practitioners.