Jeff Koons's first major installation consisted of lots of brand new vacuum cleaners placed on or attached to illuminated perspex boxes.

He claimed the works would be ruined if the vacuum cleaners were ever switched on - the whole point was that they were 'work machines' which had never 'worked'.

When I repeated this story to a mate, he said, 'What about when they were tested in the factory?'

I wondered whether Koons had ever thought of that.