‘Oh James, sometimes you can be so obtuse,’ he said crossly. ‘Of course we don’t own it. Firstly it belongs to the college, and secondly as a committed Marxist it would be quite against my principles.’

His flippancy irritated me. I decided to end the conversation by briefly humouring him. I wanted to make sure he was all right, to see him happily off into a deep sleep. I needed to get away, to see the others, to discuss what had happened. ‘But, Francis, you can’t possibly sell something like this, even if you stole it. I mean you’d be a pretty obvious suspect if the thing went missing, and then it’s such a famous picture I think that even Sotheby’s might have something to say if it wound up in their catalogue.’

‘Yes, yes, of course. That’s why we make a nice new copy of the picture, change it for the grubby old one here, and sell the original on the black market in London.’

Francis had just been punched in the face and disowned by his father, yet he seemed oddly elated. It was as if the crack on his cheek had broken the chrysalis of this plan, releasing it into the air. I was torn between dismissing the idea and changing the subject, and attempting to argue him out of it. I felt afraid of the latter, however, since it seemed that taking the time to address his ideas seriously might give them currency, promoting them from fantasy to proposition. My own feelings were still strongly flavoured with shock, and I was wary of this atmosphere – Lord Soulford’s blow had been so improbable as to create a sense of limitless possibility. If such a thing could happen, why not a multi-million-pound fraud? The logic was childishly flimsy, but it bore down on me with all the force of reason.

‘You think it’s impossible, but it’s only really one tiny step of the imagination,’ Francis said to me. ‘Remember, no rules but the ones we make. It suits the art world to give the impression that faking a master is impossible, but it is really incredibly easy. The difficult thing is faking a provenance, a history to authenticate your forgery, and even that is not impossible – John Drewe passed off paintings done in household emulsion and KY jelly as genuine Giacomettis after a few hours’ work with ink and scissors in the archives of the V and A. He just rewrote history, then stitched the new pages back into the old catalogues. During his tenure as head of the Metropolitan Museum of Modern Art, Thomas Hoving said that forty per cent of the pictures he considered for purchase were fakes. Ten per cent of all works from the French Impressionist period on the market were painted in the nineteen eighties. Salvador Dali, lying beyond understanding on his death bed, was forced to sign hundreds of blank sheets that were later turned into fake lithographs. Chagall’s widow was accused of flogging off certificates of authentication for a couple of thousand a pop. Giorgio de Chirico, sad and broke at the end of his career, forged paintings to appear to be by his younger self, the darling of the art world two decades past. And those are the tiny fraction which are ever discovered. Just consider it: hundreds of paintings hanging on the walls of the world’s most prestigious museums are no more authentic than the picture you will concoct.’