MI5/MI6's Lord Victor Rothschild accused of Working as 'Fifth Man' Soviet Spy BBC News 04Dec86

Burgess, McLean, Philby, Blunt and... Lord Victor Rothschild accused of working as 'Fifth Man' Soviet spy. Rothschild utilised Anthony Blunt, Surveyor of the Queen's Pictures, as contact-man to Soviet Embassy in London
BBC Six o'Clock News and PMQs Thu 04 Dec 1986
For the Warts and All truth check out Roland Perry's un-put-downable 'The Fifth Man' by a Jewish publisher in 1994

There is no evidence that Lord Victor Rothschild was ever a Soviet agent, Prime Minister Margaret Thatcher said Friday, a day after the banker and World War II intelligence officer appealed for an official declaration clearing his name.
https://www.latimes.com/archives/la-xpm-1986-12-06-mn-1665-story.html

Thatcher’s brief statement fell short of the request by Rothschild, who had asked Britain’s MI-5 counterintelligence service to state publicly that it has “unequivocal evidence” disproving rumors that he was the “fifth man” in the infamous spy ring of Guy Burgess, Kim Philby, Donald Maclean and Anthony Blunt.
Rothschild, 76, a hereditary peer and former adviser to former Conservative Prime Minister Edward Heath, made the request in a letter published Thursday in the London Daily Telegraph.
Thatcher caused an uproar in Parliament later Thursday by refusing to comment either way, saying that the government was still considering the plea.
“I am advised that we have no evidence that he was ever a Soviet agent,” Thatcher said in a statement issued Friday.
Exception From Policy
She said: “I consider it important to maintain the practice of successive governments of not commenting on security matters. But I am willing to make an exception on the matter raised in Lord Rothschild’s letter.”
Newspaper and radio reports Friday said that the “unequivocal evidence” was a secret 1962 meeting in London at which Rothschild nailed Philby as a Soviet agent. Philby, a former British intelligence officer, was then a Beirut-based journalist.
The meeting was also reported by author Nigel West in his 1982 book on British spies, “A Matter of Trust.”
West and the published reports said Rothschild was tipped off by a British woman, Flora Solomon, who told him in 1962 that Philby had tried to recruit her as a Soviet spy in the 1930s. Rothschild immediately arranged a meeting at his London home between Solomon and the head of Britain’s MI-6 overseas intelligence service, in which Philby had served.

Nathaniel Mayer Victor Rothschild, 3rd Baron Rothschild, Bt, GBE, GM, FRS (31 October 1910 – 20 March 1990), was a senior executive with Royal Dutch Shell and N M Rothschild & Sons, an advisor to the Edward Heath and Margaret Thatcher governments of the UK, as well as a member of the prominent Rothschild family.
Rothschild was recruited to work for MI5 during World War II in roles including bomb disposal, disinformation and espionage, winning the George Medal for "dangerous work in hazardous circumstances".
He appears several times in the book Spycatcher, which he hoped would clear the air over suspicions about his wartime role and the possibility he was involved in the Cambridge spy ring. He was still able to enter the premises of MI5 as a former employee and was aware of suspicions there was a "mole" in MI5, but felt himself above suspicion. While Edward Heath was Prime Minister, Rothschild was a frequent visitor to Chequers, the Prime Minister's country residence. Throughout his life, he was a valued adviser on intelligence and science to both Conservative and Labour Governments. In 1993, after the dissolution of the Soviet Union, six retired KGB colonels, including Yuri Modin, the spy ring's handler, alleged Rothschild was the "Fifth Man". Modin claimed, "Rothschild was the key to most of the Cambridge ring's penetration of British intelligence. 'He had the contacts,' Modin noted. 'He was able to introduce Burgess, Blunt and others to important figures in Intelligence such as Stewart Menzies, Dick White and Robert Vansittart in the Foreign Office...who controlled MI6." Christopher Andrew and Vasili Mitrokhin, in The Mitrokhin Archives, make no mention of Rothschild as a Soviet agent and instead identify John Cairncross as the Fifth Man.