In a career lasting over 30 years, Stephen Thomas served in a number of the most sensitive areas of the fight against serious organised crime. his service in the variety of these positions is unrivalled. After joining the ID in 1990, in 1996 he became an investigation officer on a Drugs Team. And then in 1997, joined an elite Target Drugs Team, investigating the highest levels of organised crime. In 2001 the author moved to the Project Team, becoming an informant (CHIS) handler, running long term, deep penetration, informants into every area of the Department's responsibilities. He went to be promoted, in 2004, to a CHIS Controller, responsible for the management of all CHIS being handled by the Project Team. Then in 2006 he joined HMRC's International Source Management Unit. ISMU managed all overseas informants run by HMRC. It was also responsible for providing training in source recruitment and management, to overseas law enforcement agencies. In 2015 he moved to the PPU, better known as Witness Protection, providing protective measures to those for whom HMRC had such a responsibility. Finally in 2017, he joined HMRC's Undercover Unit (UCU), as a Cover Officer. Throughout all of this service, Thomas was engaged in a large number of highly sensitive operations.