Mrs Theron, a retired scientific researcher, entered the serial number into Google and discovered it belonged to the Avro Lancaster III bomber, whose crew were part of 83 Squadron, of the elite Pathfinder Force.

The men had set off from RAF Wyton at 12.05am on January 3, 1944, on a mission to drop flares over targets in Berlin to light the way for the following bombers.

Flying Officer William Horace Dyke, 22, the bomb aimer, had a young son and a pregnant wife, while Sergeant John McIntyre Dunlop, 21, the mid upper gunner, had married his girlfriend just 13 weeks before his death.

The other crew members who will be honoured at next month’s ceremony were Flying Officer Ernest Blair Stiles, 22, the Canadian pilot, Flying Officer Ian Godfrey Allan, 22, the air gunner, Sergeant Joseph Banks, 22, the wireless operator, Pilot Officer Denis Charles James McKendry, 22, the navigator, and Flight Sergeant Patrick Traynor, 24, the flight engineer.

Only Dyke’s remains were identifiable, but all seven were buried alongside each other in the British war cemetery, one of two Commonwealth war cemeteries in Berlin.

Among the relatives traced by Mrs Theron and her late husband was Dyke’s younger sister Patricia Donetta.

“The men were all so young. Their average age was just 22,” said Mrs Theron. “They had hardly lived a life at all before they were killed.

“Their story is so sad, but in truth they represent thousands of young men whose individual stories have never been researched.”

As to the origins of the steel weathervane, they remain a mystery.

It was originally bought in Norfolk by a dealer who believed it came from a local farmhouse. But who made the weathervane in the shape of a Lancaster bomber – and who engraved that particular serial number on it – has yet to be established.

“That’s one thing I’ve never been able to find out,” said Mrs Theron.