London, Nov. 8 (Reuters): A man who assumed the identity of a dead baby over 20 years ago ? a ploy made famous by the Frederick Forsyth novel Day of the Jackal ? has been jailed for 21 months in Britain.

For over two decades the man who called himself Christopher Buckingham lived a relatively uneventful life, marrying and having children.

But he still refuses to reveal his real identity and even his family do not know who he is.

He was jailed for obtaining a passport in the name of the infant, who died in 1963.

Buckingham on occasion passed himself off as an aristocrat, Lord Buckingham, although the title had been extinct for hundreds of years, Canterbury Crown Court heard.

The identify theft went undetected until January 2005 when Buckingham’s passport was checked by immigration officials who found it had been cancelled two years earlier after the passport office had discovered there was an exact match with the register of deaths.

Police said the case has caused distress to the mother of the dead infant and to Buckingham’s former wife and his two children.

Investigating officer Dave Spriggs from Kent Police said it was very frustrating that Buckingham’s real identity has not been discovered.

“He just sits there and says ‘I am Christopher Buckingham’,” he told reporters outside the court.