A ‘spine-tingling’ sight used to guide the Second World War bouncing bomb during the Dambusters raid is set to go under the hammer.
It will be the latest lot in a series of bizarre items auctioned off at J P Humbert Auctionners in Towcester after Jack the Ripper objects fetched £17,000 and Charles Bronson artwork sold for more than £30,000.
The hand-made Dann sight, valued between £20,000 and £25,000, was used during the British bombing raid on the Mohne dam in Germany and is one of five Dambusters items being auctioned off.
It was the bouncing bomb, guided by the sight in 1943, which breached the Mohne dam and flooded the western Ruhr region.
On May 16, 1943, a squadron of 19 planes set out to demolish three German dams - the Eder, the Mohne and the Sorpe.
The dams were key sources of power in a major industrial area as they supplied water for steel-making, hydro-electric power and drinking water for families.
Wing Commander Guy Gibson put the squadron together in just 11 weeks and used the bouncing bomb - invented by Sir Barnes Wallis.
And the 113 crewmen were not told they would be bombing the Ruhr valley until six hours before Operation Chastise began.
The dams were protected by underwater torpedo nets that would prevent conventional bombs reaching them so Wallis took to the drawing board and designed a barrel-shaped mine.
The bomb would bounce across the water before hitting its target and then sink to explode underwater.
Gibson led the first attack at the Mohne at 12.28am but five bombs were dropped before it was breached.
The three remaining aircraft of the first wave then attacked the Eder which collapsed at 1.52am while aircraft from another two waves bombed the Sorpe.
But the Sorpe remained intact and meant the water supply in the Ruhr valley was back to its original levels within six weeks.
Although the raid was heralded as a success, it came at a high price.
Eight of the 19 Lancasters were shot down or damaged and of the 133 air crew, 53 were killed and three were captured.
But the daring nature of the raid provided a huge boost to national morale at a critical time.
Auctioneer Jonathan Humbert said: “Of all the exciting items that have come under my hammer over the years, these have to rank as some of the most spine-tingling and historical.
“We are very proud to offer these items for sale and, given their excellent provenance, we are hopeful for a great result.”“They were an integral part of modern British history and synonymous with heroism of the highest order.
The sight was designed by wing commander C L Dann and was used by bomb aimer pilot officer John Fort on board the AJ-J - the fifth aircraft to attack the dam which was piloted by flight lieutenant David Maltby.
It was passed to Maltby’s father, Ettrick, and placed in the museum of his prep school, Hydneye House in East Sussex.
When the school was sold in the mid-1950s, it was passed on to the new headteacher and eventually to the current owner - a former pupil.
The auctioneers is also offering a map light and parallelogram used by sergeant Vivian Nicholson - Matlby’s navigator on the same aircraft - as well as four of the marbles used to design the bouncing bomb and a leather collar box which belonged to the commanding officer for the mission.
The International Militaria Auction takes place at the auctioneers in Silverstone Business Park on January 20.