The unnamed woman, thought to be an immigrant, managed to travel on the British passport of Carol Anne Keast for over a decade without arousing suspicion.
Her astonishing deception only came to light after the real Carol Anne Keast tried to renew her passport and was interrogated to find out whether she was who she claimed to be.
The 53-year-old then had to provide old school records to back up claims that she was the real Ms Keast.
It was only then that the bogus Carol Anne Keast was finally arrested while on a break in Marbella with her unsuspecting television producer boyfriend.
Yesterday she was beginning a nine-month prison sentence for fraudulent use of a passport – but is still refusing to divulge her real identity.
Her victim, who has used her married name of Carol Anne Pinton since 1982, told the Daily Mail: “It’s a bit silly really because mine is a very unusual name and she is apparently about 20 years younger than me.
“She is of African appearance and I am not, neither are any of my family. How she thought she was going to travel and get away with it I will never know.”
Prosecutor Sol Broady said: ‘She is wilfully refusing to identify herself properly, or give her country of origin.
Judge Jonathan Greake told her: “You fooled a number of people and having been living a lie got a number of years. Your real identity it would appear to everybody remains something of a mystery.