Julian Mardon, who had been in jail in Canada for offences against children, admitted 16 charges.
He was sentenced to 16 years. He was found not guilty of nine other offences, following a trial at Bristol Crown Court
Mardon was arrested on arrival at Heathrow Airport in March.
The offences he admitted to related to three boys, who were aged between 11 and 16 at the time.
Speaking after sentencing Det Sgt Katherine Davis said Mardon was a "dangerous man with a deplorable track record of being able to manipulate and influence people in order to abuse children".
"Mardon was serving a prison sentence in Canada for similar offences committed against children during his time there and he was deported following his release from prison," she said.
An 81-year-old man who was deported from Canada has been jailed for sex offences against children in Bristol in the 1970s.