LONDON — They were shaped like cigars, saucers, coffins and amorphous blinking blobs. They hovered in a menacing manner, traveled at impossible speeds and vanished into the netherworld, or, in one instance, a hedge in Cornwall.

A few carried humanoid life forms, or so it seemed. A few materialized courtesy of the observers’ possibly having had a drink too many, as in the case of an unidentified flying light cluster witnessed loitering in the sky by the patrons of a pub in Kent.

Whatever they were, these phenomena reported to Britain’s Ministry of Defense over the years and made public this month were almost certainly not actual alien aircraft piloted by actual alien beings.

“The government has been telling us the truth,” declared David Clarke, a senior lecturer in journalism at Sheffield Hallam University, who has a side interest in U.F.O.’s. “There are a lot of weird things in the sky, and some of them we can’t explain, but there’s not a shred of evidence for a single alien visitation.”