In October 1988, John McCann, Finbar Cullen and Martina Shanahan, all from the Republic of Ireland, were convicted at Winchester Crown Court of conspiracy to murder King near his home in Wiltshire and sentenced to 25 years in prison.

The Court of Appeal ruled that their trial could have been prejudiced by comments made by King who said the defendants should not have the right to remain silent.

He left the Cabinet following the 1992 general election, and returned to the backbenches where he served as Chairman of the Intelligence and Security Select Committee from 1994 to 2001, during which time KGB agent Vasili Mitrokhin defected to reveal 87-year-old Melita Norwood as a Soviet spy.

He serves as Deputy Chairman of the Conservative Party's Policy Group on National and International Security, which was set up by David Cameron in 2006.

King was the subject of a song in the satirical ITV programme Spitting Image in which he was depicted as the Invisible Man during his term as Employment Secretary.