Nor iron bars a cage...

Prison art can have the power of redemption. Its value was championed 40 years ago by Arthur Koestler, author of the prison novel Darkness at Noon and himself once a political prisoner. He founded the Koestler Trust, which encourages prisoners to develop their creativity and awards small annual prizes to several hundred inmates.

Two thousand of this year's art works (ranging from paintings that reveal the troubled minds of the artists, through traditional matchstick 'sculpture', to ceramics and needlework, photos and woodwork) go on show on September 14 at the Trust's HQ, the highly atmospheric one-time home of the governor of HMP Wormwood Scrubs, just outside the jail gates. The work - by prisoners, detainees and high-security hospital patients - is on sale at prices between £10 and £1,000.