LONDON, England (CNN) -- Ailing "Great Train Robber" Ronnie Biggs -- one of the most notorious British criminals of the 20th century -- was formally released from prison to his death bed Friday after being granted his freedom on compassionate grounds.
Ronnie Biggs, pictured at a book launch in Rio de Janeiro in 1994.
Biggs, who is gravely ill with severe pneumonia, is being cared for at a hospital in Norwich, eastern England, where he was moved on Tuesday.
Three prison staff who had been assigned to Biggs' bedside have been withdrawn following UK Justice Minister Jack Straw's decision to authorize his release, a Ministry of Justice spokesperson told CNN.
"The medical evidence clearly shows that Mr Biggs is very ill and that his condition has deteriorated recently, culminating in his re-admission to hospital," Straw said in a statement Thursday. "His condition is not expected to improve."
Biggs' son, Michael Biggs, said his father was "over the moon" that he had been released on the eve of his 80th birthday. Speaking to reporters outside the hospital, he confirmed his father had been handed his release papers.
"As a family, we are absolutely thrilled," Michael Biggs said, according to the UK's Press Association.
Biggs is unable to walk, barely able to communicate and no longer able to eat or drink, Michael Biggs said, adding that the family was "very hopeful that my father will be able to survive the next few days."
Biggs' legal advisor Giovanni Di Stefano told journalists that Biggs was unlikely to ever leave his hospital bed. "This man is ill, he's going to die... he is going to stay in hospital," he said.
Saturday also marks the 46th anniversary of the infamous 1963 heist dubbed the "crime of the century" that transformed Biggs from a petty London thief into one of the most wanted men in Britain.
Biggs and 14 other professional criminals made off with more than £2.5 million ($4.2 million) in used bank notes -- the equivalent of around £40 million ($67 million) today -- after holding up a mail train from Glasgow to London in the early hours of the morning. In the course of the robbery the train driver was badly beaten with an iron bar.
Most of the gang, including Biggs, were soon picked up in a massive manhunt after police discovered fingerprints at a farmhouse hideout where the robbers had holed up to split their spoils.
Biggs was sentenced to 30 years in prison but escaped over the wall of a London prison after serving just 15 months -- and spent most of the rest of his life as a celebrity fugitive.
After undergoing extensive plastic surgery in Paris, Biggs made his way to Australia, living there with his wife and two children. Tracked down by police, Biggs fled again in 1969, this time to Brazil.
Five years later, Biggs was traced once more by a newspaper reporter. Metropolitan Police Detective Superintendent Jack Slipper, who had led police efforts to bring the train robbers to justice, flew out to Rio de Janeiro to arrest Biggs, allegedly greeting him at a beachside hotel: "Long time no see, Ronnie."
But efforts to bring Biggs home were frustrated because by then he had fathered a Brazilian-born son -- Michael Biggs -- and authorities rejected British requests for his extradition.
Biggs continued to live openly in Rio, trading on his notoriety by entertaining tourists, selling t-shirts and even recording with the Sex Pistols.
In 1981 he was kidnapped by a gang of British ex-soldiers and smuggled to Barbados. But legal efforts to have Biggs brought back to the UK once again stalled and he was allowed to return to Brazil.
By the late 1990s Biggs was in poor health following a series of strokes and running out of cash. In 2001 he flew back to the UK on a private jet laid on by the Sun newspaper. He was promptly locked up in a high security prison but then moved to a facility for elderly prisoners.
Since his return Biggs and his family have campaigned for his parole on compassionate grounds -- an appeal until now rejected by successive justice ministers on the grounds that Biggs had never shown any remorse for his actions.
Michael Biggs said his father had expressed regret for the robbery -- but not for the life he had led in the years since the crime.