For decades John Livesey, known as Jack, told friends, colleagues and his closest family that he had served with distinction in the Parachute Regiment.
He even claimed on his website that he had advised production crews working on the films Saving Private Ryan and Band of Brothers. In fact his army career amounted to a stint in the Catering Corps between 1971 and 1974.
The 57-year-old’s lies came to light following his conviction for benefit fraud in 2004 when he produced references from genuine veterans who had been taken in by him.
Earlier this month he was found guilty of perverting the course of justice at Peterborough Crown Court.
Passing sentence yesterday, Judge Nic Madge said: “Much of your life since 1974 has been a lie.”
Roger Harrison, in mitigation, said his client had been diagnosed with histrionic personality and dependent personality disorders.
He said this meant his client could not tell “fact from fiction”.
He added: “He had established himself as a respected military historian. Obviously he has now lost that reputation and lost his occupation.”
Mr Harrison said his client was physically disabled and had restricted mobility.
Previous psychiatric reports found no evidence of such disorders and Judge Madge questioned Livesey’s physical disabilities.
He said: “One day after court I saw Mr Livesey near the court building and his mobility seemed significantly better than it did in court.”
He added that previously medical examinations had found Livesey was prone to exaggerating his psychological and physical conditions.
Livesey was caught out after he falsely claimed £30,000 in benefits while working at Duxford’s Imperial War Museum.
Following his conviction in 2004, he provided references from veterans including Air Commodore Peter Thorne and Maj Gordon Corrigan, who served in the Royal Gurkha Rifles and was made an MBE in 1995.
He told those who knew him he reached the rank of Colour Sergeant and that he was awarded a medal for gallantry after serving in the Falklands and Northern Ireland.
But police investigations found Livesey had misled everyone who knew him.
In truth, he was discharged from the army in 1974 after he threw himself from a bedroom window in an apparent suicide attempt following a four-month spell in Northern Ireland.
Livesey, of Purley-on-Thames, near Reading, Berkshire, had denied perverting the course of justice at Peterborough Crown Court but was convicted earlier this month.
As well as jailing Livesey for three years, the judge also ordered him to pay £3,500 in prosecution costs.