With a background as a Criminal Defence Solicitor-Advocate Leslie is currently engaged In a number of diverse roles. These include judicial work sitting as a Recorder in the Crown Court and as a Tribunal Judge of the Mental Health Tribunal, the Special Education Needs and Disability Tribunal and the Social Security and Child Support Appeals Tribunal.

Leslie also adjudicates Road User Charging appeals, is one of the Independent Adjudicators for Companies House and is a Legally Qualified Chair of the Police Misconduct Panel.

Leslie has been a trainer of investigators and lawyers in a variety of skills, is the Lead Advocacy Trainer of the Solicitors Association of Higher Court Advocates (SAHCA) and trains on a number of courses for the Judicial College of England and Wales as well as the European Judicial Training Network (EJTN).

He is the Managing Director of Independent Investigative Interviewing Limited which conducts disciplinary, grievance and complaints investigations for companies which lack the resources or skill mix to undertake them.

He is the author of two books 'Effective Interviewing for Disciplinary, Grievance and Complaints Investigations' and '365 Daily Advocacy Tips', published by Bloomsbury Professional Publishing, and is currently working on a book focussing on judgecraft.’