Great Train robber Ronnie Biggs is likely to be freed by Valentine's Day next year, said a family spokeswoman.
Judy Totton told the BBC News website: "We understand that this is what the government has indicated. We are very very hopeful."
The Ministry of Justice said it did not comment on individual cases.
Biggs was jailed for 30 years for his part in the 1963 robbery but escaped and went on the run. He returned in 2001 to serve the rest of his sentence.
Biggs, 79, has been in poor health after suffering a series of strokes and heart attacks.
His son Michael has long campaigned for his father to be released on compassionate grounds.
Ms Totton said: "It was such a long sentence in comparison to the sentences meted out nowadays."
The Guardian reported that plans were under way to find a private nursing home for Biggs in north London, to be near his son.
Ms Totton said she did not know on what basis Biggs would be released.
But she said she had spoken to Michael Biggs, who was in Brazil, and he also seemed hopeful that his father would be freed soon.
A Ministry of Justice spokeswoman said prisoners could be released on compassionate grounds, for example if a person was suffering from a terminal illness or where they were bedridden.
Biggs was transferred from the high security Belmarsh prison, in south-east London, in June 2007 to a unit at Norwich Prison for elderly inmates on life sentences, on compassionate grounds.
Biggs had served only 15 months of his 30-year-sentence when he escaped from Wandsworth Prison.
He was on the run for 35 years after fleeing to Paris and Australia and then Brazil.
His lawyers have previously written to the Parole Board arguing Biggs should be released having nearly served a third of his sentence including time spent in custody abroad.
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