RAF controllers told US pilot Milton Torres to “lock on” and launch all 24 of his rockets over the city.
But as he came within seconds of firing at the alien intruder — “the size of an aircraft carrier” on his radar — it vanished at 10,000mph.
The amazing close encounter is revealed in secret Ministry of Defence X-Files which are declassified today.
Milton said: “It was some kind of alien snooping over England. I guess we’ll never know what it was.”
The incident happened in 1957 when Milton was a 26-year-old US Air Force lieutenant based at RAF Manston in Kent.