On the evening of August 4, 1990, two men walking on the moors above Calvine in Perthshire said they saw a large diamond-shaped craft hovering silently. They hid under some trees and took six photos before it shot straight up and out of sight. A military jet appears in the pictures.
The men gave the prints and negatives to the Daily Record newspaper in Glasgow, which passed them to the Ministry of Defence. The newspaper never ran the story, the original film disappeared, and the witnesses have never been identified.
For decades only a drawing was known. In 2022 journalist David Clarke found a print of the best photo kept by a retired RAF press officer, and it was published widely. Ideas include a secret aircraft, a rock reflected in still water, and a hoax.