JOHN Yates headed the UK's Counter-Terrorism Command and was the UK's most senior Counter Terrorism Officer with responsibility for royalty, diplomatic and close protection, aviation security and the Houses of Parliament - as well as all counter-terrorism preparations for the 2012 London Olympics - before he retired last November.
The former Assistant Commissioner for the Metropolitan Police Service was named head of the UK's Specialist Crime Directorate in 2008 and led the British police response to the Southeast Asian tsunami in 2004, which saw him honoured with the Queen's Police Medal.
During his 30 years of service he advised both the British Prime Minister and National Security Council on counter-terrorism and was also involved in investigating police corruption.
High-profile cases he has led include an investigation into the July 2005 shooting of Jean Charles de Menezes - known as the Stockwell shooting - in which an innocent man was shot and killed by police in London following terrorist attacks on the transport network.
As head of a special inquiry squad Mr Yates also handled a series of sensitive cases including the conviction for perjury of novelist and former Conservative party chairman Lord Archer.
He was also part of a 16-month investigation into the cash-for-honours scandal that ended in 2007.