Great Train Robber Ronnie Biggs is set to appeal against the government's decision to refuse him parole.
Justice Secretary Jack Straw rejected a recommendation by the Parole Board which backed the release of Biggs, 79.
Mr Straw said Biggs was "wholly unrepentant" about his actions and had "outrageously courted the media".
Biggs's son Michael told the BBC's Today programme his father would appeal against the decision because he had expressed remorse in his autobiography.
Reacting to Mr Straw's decision, Michael Biggs said: "I'm very upset.
'Regretted his crime'
"He said in his autobiography he showed remorse.
"My father has always stated 'I regret committing a crime, but I do not regret how I have spent my life because I got a family and loving son.
"We're going to appeal the decision... we have to continue fighting."
Biggs is currently in the Norfolk and Norwich University Hospital after breaking his hip in a fall.
He was taken from Norwich Prison to hospital after the fall at the weekend.
Michael Biggs is expected to visit his father later.
The Parole Board report said the risk Biggs posed was "manageable under the proposed risk management plan and consequently parole is recommended".
But the panel added that "in terms of his attitudes and risk areas" there was little evidence, apart from his increased age, to suggest he would not return to his old criminal lifestyle.
Giving his reasons for the refusal of parole, Mr Straw said it was "unacceptable" that Biggs had chosen not to obey the law and tried to avoid the consequences of his decision.
In announcing his decision on Wednesday, he said: "Mr Biggs is wholly unrepentant and the Parole Board found his propensity to breach trust a very significant factor."
Biggs was a member of a 15-strong gang which intercepted an overnight train in a quiet part of Buckinghamshire.
The robbers struck on 8 August 1963 when the train stopped near Cheddington after the gang had changed a signal to red.
They escaped with £2.6m in used banknotes in the biggest ever raid on a British train.
After being given a 30-year sentence, Biggs escaped from Wandsworth Prison, south London, in a furniture van after spending 15 months in jail.
He was on the run for more than 30 years, living in Spain, Australia and Brazil, before returning to the UK voluntarily in 2001.