The conmen gained the trust of the elderly couple by offering condolences for their daughter and son-in-law. They had photograpahs in the room of both of them.
There were also photos of Harold's mum receiving a telegram from the Queen on her 100th birthday and a picture of the ship he served on during the Second World War - a mine sweeper that took part on D-Day.
The conmen then started doing a bit of work on the wall and said there was a problem with a bush near the house; the roots were affecting the foundations and urgently needed to be removed. They then insisted on being paid £3000 in cash.
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Lee Curley took more than 120 pictures and videos of his attacks on the girl, said to be under the age of 13.
Council workers uncovered the AK-74 concealed in the undergrowth.
The thief, who used a walking stick, was helped by a man who disabled the lock before pushing the woman away.