The politician implicated in an alleged child sex ring at 10 Downing Street was Sir Peter Morrison, one of Margaret Thatcher’s closest advisers, IBTimes UK can reveal.

Morrison was the mystery “senior aide” MP Tom Watson alluded to at Prime Minister’s Questions (PMQs). Watson’s allegation of a paedophile ring close to Downing Street stunned the House of Commons.

Morrison was a Conservative politician who acted as Thatcher’s parliamentary private secretary while she was prime minister. He also masterminded her failed bid to hold on to the leadership in 1990.

Morrison left office in 1992 and died in 1995.

The sexual tastes of the prime minister’s trusted adviser were an open secret in some quarters but were concealed by a police cover-up and threats of libel by Morrison himself, according to a former editor of the Sunday Mirror, Peter Connew.