Minutes of the Joint Intelligence Committee (JIC), Cabinet Office, Whitehall, 1957 (PRO CAB 159/37)
Meeting 38 (11 April 1957):
1. AERIAL PHENOMENA. Air Vice Marshal MacDonald [ACAS(I)] informed the Committee that there had recently been reports of a number of unexplained aerial phenomena. All these phenomena had, however, been satisfactorily explained through mistakes in radar interpretation, maladjustment of sets, as balloons or even as aircraft.
1. Took note.
2. Invited the Air Ministry to prepare a short note for inclusion in the Red Book [JIC Intelligence Monthly digest]
[NOTE: Subsequent to the meeting the Secretary was informed that the Air Ministry were preparing the note for inclusion in next week's Red Book.]
The Red Book entry, No 59 12-17 April 1957
UNIDENTIFIED FLYING OBJECTS [SECRET]
7. Reports of unidentified flying objects are received at the rate of approximately one a week. Since 1st January 1957, sixteen reports from official and unofficial sources have been received. A satisfactorily explanation has been found to account for ten of these sightings, two remain unexplained and the remaining four are under investigation.
8. The ten explained incidents were due to nothing more alarming than meteorological balloons (1 case), aircraft navigation lights (2 cases), aircraft flares (2 cases), Meteorite (1 case), an engineer's amateur experiment (1 case), one case of a photographic hoax, one of faulty radar equipment, and a Newspaper review of a book published on German Wartime Weapons.
9. Lack of evidence and a cold scent account for one of the two unexplained incidents and the other might feasibly have been a meteorological balloon but this cannot be confirmed.
10. The remaining four incidents still under investigation are all radar sightings. In each, unusual behaviour of the radar blips in terms of course, speed and heights were reported. Attempts are being made to trace the cause of these sightings to aircraft known to have been near, inexperienced operators or spurious echoes of unexplained origin.