Genial academic medic and doughty campaigner. Distinguished career at St Mary's, Paddington, and Guy's hospitals. World expert

on diabetes. Helped found the pressure group NHS Support Federation in 1989 in response to Mrs Thatcher's market reforms.

What did he think of the internal market?

Made medicine money-obsessed; treated patients like business units. Worst of all, he says, it didn't even work. 'If people were getting better treatment, more quickly and effectively, I would have found it difficult to oppose.'

So he was not exactly a Tory favourite?

His former Guy's consultant colleague Lord (Ian) McColl once denounced Professor Keen in the House of Lords as a Communist sympathiser. The noble Tory Lord phoned him to apologise, and sent him two bottles of whisky as recompense.

What does he make of the market's successor?

'I do not like the purchaser-provider split. Some of the old idiocies are being got rid of, but has it changed for the better? I'm not yet convinced.'

Where is he now?

At 72, he's emeritus professor of human metabolism at Guy's, president of the International Diabetes Federation, and still president of the NHS Support Federation.

Any regrets?

The Tory election win of 9 April 1992: 'One hoped we would have been able to stop the reforms at an earlier stage.'

Remaining ambitions?

Political: to see the NHS replace the private finance initiative with public bonds, and make the service more publicly accountable. Professional: to see the barriers between hospital-based care and primary care break down. Personal: 'To stay alive as long as possible.'