Watching a recent documentary called Cocaine Cowboys about the growth of the drug trade in Miami in the 1980s, I was reminded that many forms of crime are simply uninhibited capitalism – but on an illegal basis.

That implies that prisons are likely to be full of entrepreneurial talent that has strayed to the dark side. Moreover, there are plenty of hugely successful business leaders who have spent time inside, including Gerald Ronson, Martha Stewart and Lord Black, who is just starting his sentence in Florida.