The facts are these:
He, with others, was found guilty of the so-called Great Train Robbery of 1963.
He was sentenced to 30 years, but escaped in 1965, went on the run, eventually ending up in Australia.
At some point, for obvious reasons, he had plastic surgery on his face.He was eventually "rumbled" in Oz, so legged it to Brazil, was given citizenship, was farcically "kidnapped" but returned to Brazil to resume his life of stolen freedom.
In 2001, in poor health, he "voluntarily" (with the connivance of the Sun) returned to the UK, where he has been incarcerated since.
By my reckoning, therefore, he has served less than 10 years of his 30 year sentence.
Why should he be released now that he's ill and frail? He wasn't so ill and frail all those years he spent having the "Life of Riley" in Oz and Brazil instead of getting the vertical sun tan he deserved.
If you can't do the time, don't do the crime!