His interest in military planes began when he watched US Army Air Force bombers taking off and landing at a nearby airfield during the second world war.

His interest in military planes began when he watched US Army Air Force bombers taking off and landing at a nearby airfield during the second world war.

But aviation enthusiast Bertie Ashby was last night praised for preserving an important part of Anglo-American military heritage after making a huge donation to save the UK's only airworthy B-17 Flying Fortress.

The pensioner from Wymondham is looking forward to attending the Imperial War Museum at Duxford, near Cambridge, at the weekend when the Sally B takes part in her first memorial flight in 18 months.

It comes after Mr Ashby donated �360,000 following the sale of some land to return the second world war bomber to the skies after a major mechanical fault.

Officials from the B-17 Charitable Trust spoke of their delight as they prepared to return to the air show scene following the generosity of the retired builder.

The iconic aircraft - painted in the livery of the 457th Bomb Group from the USAAF 8th Air Force - has been appearing at memorial flights, flypasts, and rallies for the more than 30 years, but has been grounded by engine problems since October 2007.

Elly Sallingboe, B-17 operator and chairman of trustees, said the charity's biggest donation had saved the more than 60-year-old bomber from becoming a permanent static museum display.

'It's no exaggeration to say Bertie Ashby is our saviour. We had to buy three new engines over the last three months and without his donation we would be finished.

'People are surprised to learn that we get no official support whatsoever, and the series of engine problems we faced last year, coming after the 2007 season was virtually washed out by the weather, almost drained our coffers,' she said.

The Sally B, which is based at the Imperial War Museum, will be flying at the Spring Air Show at Duxford and completing a 95th Bomb Group memorial flypast near Eye on Sunday.

The aircraft flies as a living memorial to the USAAF aircrew who flew daylight missions over Europe in B-17 Flying Fortresses from bases throughout East Anglia between 1942 and 1945 and pays tribute to the 79,000 Allied airmen who lost their lives during that time.

Mr Ashby, who has lived in Wymondham all his life, began a life-long interest in American second world war planes after watching 389th Bomb Group Consolidated B-24 Liberators flying from Hethel Airfield between June 1943 and May 1945.

The master builder later became a regular visitor to the military museum at Duxford and struck up a friendship with fellow Norfolk man, Peter Brown, Sally B's chief engineer.

Mr Ashby has since been made an honorary member of the Sally B team and appears on the plane's roll of honour following his outstanding gesture.

It costs around �350,000 a year to maintain the 50,000lb Flying Fortress, which is supported entirely by donations and its 6,500 supporters.

Ms Sallingboe added: 'It's always been a constant struggle to make ends meet and keep Sally B flying, but without his generosity, along with the continuing loyal support of our friends, sponsors and supporters, we wouldn't have got through the dark times to see her in the air again, where she belongs.'

For more information, visit www.sallyb.org.uk.