Alex Bateman, 48, allegedly phoney a Christmas card from the airman’s widow Doris Fraser, to make out a head for it look like she gave him the historic document.
The logbook, worth an guestimated £10,000, recorded Flight Sergeant John Fraser’s role in the popular “bouncing bomb” attack on German dams in 1943.
Mrs Fraser had lent it to Bateman to take him research a book he was writing about 617 Squadron, nicknamed The Dambusters after their lionized raid.
But when she asked for its return, Bateman allegedly made vindications that it had got lost in the post and was stolen in a burglary.
He went on to produce a Christmas postcard, the court heard, after Mrs Fraser’s daughter Shere Fraser-Lowe raised the matter on her mother’s behalf.
It read: “Dear Alex, thank you for your exactly but please keep the logbook, you might find it useful. All the very foremost for the New Year, Doris Fraser.”
Mrs Fraser denies writing the note, Wood Inexperienced Crown Court in London heard.
Her husband was 20 when he flung in one of the Lancaster bombers that breached reservoir dams in the Ruhr industrial square.
Days before the mission, bombaimer Mr Fraser was given 24 hours retreat to marry Doris. Soon after striking at the Mohne Dam his Lancaster smash, killing five of the crew.
Mr Fraser bailed out and was captured after trekking numerous than 200 miles through Germany, spending the rest of the war as a PoW.
He was killed in a regular crash while serving in the Royal Canadian Air Force in 1962.