The man assumed the identity of a nine-month-old boy called Christopher Edward Buckingham, who died in 1963, to perpetrate what a judge described as "wholesale identity theft".
In January, UK Immigration officials checked his passport at Calais and realised it had been obtained by deception.
He claimed to detectives he was a hereditary peer who sat in the House of Lords, but further checks revealed he had assumed the name using the same method as the professional killer in the novel The Day Of The Jackal.
Last month the man, whose ex-wife and two children also do not know his true identity, pleaded guilty to making an untrue statement for the purpose of obtaining a passport.
Today he was sentenced at Canterbury Crown Court by Judge Adele Williams, who criticised him for his "lack of remorse" and "active obstruction" of the authorities.
Trevor Wright, prosecuting, said the case appeared to be "fairly straight forward" at first when the man was arrested after arriving at Dover in a Swiss-registered car.
However, Mr Wright said that as the case unfolded, what emerged was a fraud which was "wicked and contemptible" and also "astonishing and complex".
He said police had found headed notepaper in the man's car with a crest referring to "Lord Buckingham" of Little Billing, Northamptonshire.
Detectives discovered that the coat of arms used in the crest did indeed resemble that of the Duke of Buckingham.
However, despite the man's claims in interview that he was entitled to sit in the House of Lords, further checks unravelled the true story that the name Christopher Buckingham had been taken from a birth certificate.
Mr Wright told the court that the real Christopher Buckingham was born in 1962 in Lambeth, south London, but had died in a tragic incident in Bognor Regis the next year.
Detectives discovered that a chequebook, BT account and credit card used by the man were all registered in the name of Lord Buckingham.
He told police in interview that he had been born in Lambeth but said that he had travelled widely as a child and claimed his mother was born in 1952.
Mr Wright said that these statements showed that the man had failed with some "elementary arithmetic" because it would have made his mother 10 at the time of his birth.
Claims that he had been to Harrow and that both his parents had died in an air crash also proved to be false when police looked at Christopher Buckingham's actual background.
Mr Wright said that DNA analysis finally settled the matter when police contacted the mother of the dead child Audrey Wing, who is still alive and lives in Scotland.
She said her baby died on a caravan holiday on the south coast in a tragic accident.
Mr Wright said Mrs Wing was severely "traumatised" by the revelations that a man had been using her dead child's identity and a medical report revealed she was now subject to nightmares.
- More about: