Alexander Bateman, of Headstone Lane, was jailed for two years at Wood Green Crown Court on Friday (February 10).
Bateman, a military historian, was loaned the artifact by the victim in 1996 as part of his research into RAF airmen in the legendary Dambusters squadron.
Over the years he attempted multiple deceptions in an attempt to keep the document from the woman, the Metropolitan Police said.
Acting Detective Sergeant Henry Childe, from the Metropolitan Police Falcon Unit, said: “In stealing this priceless piece of WWII history through deception and lies, Batemen also deprived the victim of one of her lasting memories of her husband, an RAF war hero.
“Over the course of many years, Bateman went to great lengths to cover the tracks of his theft by insisting that the book was lost.
“He then gave the family false hope by informing them it had been recovered but avoided further contact, and finally said it had been stolen in a burglary.
“Today's sentence is due punishment for Bateman's deplorable actions and I hope that the victim and her family take some comfort from the fact that Bateman has finally been brought to justice.”
Logbook never recovered
The logbook has never been recovered and Bateman refuses to tell anyone what happened to it.
He first contacted the victim, who lived in Canada, in 1996 as part of his research, asking if she could send photographs or logbooks belonging to her late husband.
The victim sent the document to help with his research, before the daughter asked for it back in 2003 after she learned Bateman still had it.
An envelope arrived from Bateman, but it had been carefully sliced open at the bottom, and a piece of card and a letter from Bateman were found stapled to the inside - but no logbook.
He first said that the logbook must have been stolen, but then said he had recovered it from the Post Office.
His story then changed when he said he had been given the artifact without condition, and later forged a Christmas card from the victim which said he could keep the logbook.
Bateman started ignoring calls
Bateman stopped returning calls and reported a burglary in June 2003, claiming intruders broke in and stole the logbook – the day before a national newspaper published a story about the dispute which was being pursued as a civil claim by the victim's family.
The burglary investigation found no suspects and no forensic leads.
In March 2015, the dispute was reported to Action Fraud and referred to the Met's Falcon Unit.
Almost certainly not victim's handwriting
Officers attended Bateman's address and handwriting experts analysed the Christmas card, they found it was almost certainly not written by the victim, the police said.
Bateman was charged in July 2016 with theft and was found guilty after a five day trial at Wood Green Crown Court on January 13, 2017.
Anyone with information as to the whereabouts of the late Sergeant John Fraser's missing logbook should contact A/DS Childe on 020 8345 4552 or call Crimestoppers anonymously on 0800 555 111.
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