Biggs, 67, who escaped from Wandsworth Prison after being given a 30-year sentence for his part in the 1963 robbery, which netted pounds 2.6m, said: "I don't think I would run because, number one, I can't afford to. I don't have a current passport to go to another country." He told the BBC: "In the event of the Brazilian government deciding I must go back, then go back I shall ... prisons are much better these days, so I've heard."
Biggs, who lives in Rio de Janeiro with his son Mike, added that he would return to a British prison with equanimity.
"I ... don't visualise myself going back to prison for such a long time ... possibly I'd get out in something like six or seven, perhaps eight years and I could possibly do that.
"I'm going to be pretty old when I get out but there's a lot of old people going to prison today and they get through it somehow ... I've always said I'd be quite happy to spend my twilight years in jail and not be a nuisance to loved ones around me, as it were."
While Biggs insisted he would not go on the run again, he did say that he would "of course" fight extradition.