My former mother-in-law once bought quite a minor old master at a country sale. Reverently she wrapped it in sacks and old copies of the Guardian, laid it in the boot of her Mini and slowly drove it home. On arrival she noticed it was rather tight in its frame so she lovingly placed it face downwards on the kitchen table and gave it several hefty blows with a large hammer. Turning it back over, she discovered great chunks of the surface had fallen off.

Did she panic and call in the experts? On the contrary she scuttled off to another wing to find a tube of old glue and began simply sticking the bits back, sometimes in the right place.

Now there is a school of modern art restorers who say she was right. They