Speculation is growing that Great Train Robber Ronnie Biggs will be freed from prison this summer.
The case for Biggs' early release is due to be heard at a Parole Board hearing in July.
His son Michael said he was expecting his father, now 79, to be freed by the authorities and to move to a care home.
He told ITV News: "Hopefully, everything is working the way we want it to work, he will be able to move to a nursing home as due to the level of care that my father needs I will not be able to look after him.
"I've been visited by the probation officers and the parole officers. We had several discussions on what life on the outside would be like for my father and what local impact it would have on the community and of course what kind of impact it would have on him and his health."
He added: "I think the public will be appalled to see what state my father is in once he gets released from prison. I don't think people are expecting to see someone so frail and so old.
"Perhaps the government was not hoping that he would last this long, but he has, and now that he has done his time they have to let him out."
Biggs, from Lambeth, south London, was a member of a 15-strong gang which attacked the Glasgow to London mail train at Ledburn, Bucks, on August 8 1963 before making off with £2.6 million.
He was given a 30-year sentence but escaped from Wandsworth prison, south London, in a furniture van after spending 15 months in jail. He was on the run for more that 30 years, living in Spain, Australia and Brazil, before returning to the UK voluntarily in 2001.
Earlier this week the inmate was returned to Norwich Prison from hospital where he was being treated for a bout of pneumonia.