It is one of the most tantalising ever official accounts of an encounter with a UFO – deemed so credible it even convinced the government minister who investigated it.
Now, for the first time, the sighting of a flying saucer by an RAF fighter pilot and the subsequent high level inquiry it prompted can be revealed.
The sighting occurred in 30 July 1952, when Flight Sergeant Roland Hughes was on a training flight over West Germany in a de Havilland Vampire FB9.
As he was returning to base, he reported being intercepted by a "gleaming silver, metallic disc" which flew alongside his aircraft before speeding off. The mystery object was also detected by RAF radars on the ground, which recorded it travelling at speeds far in excess of any known aircraft.
Hughes reported the sighting to his senior officers who sent him to see Duncan Sandys, the then aviation minister, to brief him personally.
The UFO sighting is not only one of the most detailed by a serving member of the armed forces but also shows how seriously such reports were taken by the authorities. British governments have historically downplayed the suggestion that such sightings have been investigated.
The existence of the sighting has emerged in papers released by the Churchill Archive, at Cambridge University. The centre contains the papers of Sir Winston Churchill, as well as Sandys, who married the former prime minister's daughter, Diana.
In one document – written a few days after the interview with the 23-year-old Hughes – Sandys tells the government's chief scientist, Lord Cherwell, about the meeting and states that he found the airman's account and the supporting evidence from radar "convincing".
The sighting came shortly after a number of similar "flying saucer" reports from US airmen and Sandys added: "I have no doubt at all that (Hughes) saw a phenomenon similar to that described by numerous observers in the United States."
Lord Cherwell had dismissed the US sightings as "mass psychology", but in his memo Sandys takes him to task for this attitude and makes clear his position on the existence of UFOs.
The minister, who was later promoted to Defence Secretary, went on: "Until some satisfactory scientific explanation can be provided, it would be most unwise to accept without further question the view that 'flying saucers' can be dismissed as 'a mild form of hysteria'." Sandys also wrote that there was "ample evidence of some unfamiliar and unexplained phenomenon".
The UFO sighting that convinced a Government minister - Telegraph