Mark is both a civil and criminal litigation specialist who conducts the majority of his work in the area of Financial Services, often against the State, in particular HMRC, the Serious Fraud Office and the Financial Conduct Authority. Many of his cases conclude in the Supreme Court and the European Court of Human Rights and involve real points of principle.

Mark has been involved in many notable and interesting cases since the establishment of the SFO and he is often called upon by the media to offer comment on matters of national interest. He travels abroad regularly to meet with clients who are unable to travel to the UK. Mark joined Keystone Law in 2009 after 20 years heading up the White Collar Fraud department at Jeffrey Green Russell. Prior to that he was a partner at Titmuss Sainer & Webb (now Dechert) where he spent a total of 9 years.