Diamonds are every urban art guerilla's best friends

Okay, to recap. And do bear with me if I get a little tearful, as stories such as this do place great strain on my ability to cope with modern life. Banksy, that damned elusive pimpernel of guerilla street art and a man born without a face (making it almost impossible for him to find fashionable sunglasses), wanted to pass comment on the use of sweat-shop child labour to produce Diamond Jubilee bunting last year.

Like me, I'm sure you spent a lot of last Summer in a glee-induced coma that our beloved monarch had managed to stay rich and unelected for an impressive 60 years, in the face of a relentless onslaught of unfettered toadying.

To do his satirical part, Banksy found a wall, shook his cans of paint and sprayed the image of a boy hunched over a sewing machine, out of which was hanging an actual string of Union Jack flags. Such pith! Possibly to compound his disdain for the Western sale of cheaply produced goods, the child was painted on the side of a Poundland store in London. With me so far? (Quick point of order: Poundland has gone to some lengths to deny using sweatshop-based child labour. Mind you, given that everything it stocks costs a quid, its margins are so low that it is always going to be outbid when it comes to attracting scab-kneed urchins).

Anyway, last Wednesday scaffolding appeared around the gilded wall, with "tarpaulins of secrecy" used to obscure whatever shenanigans were going on. Come Saturday, the ad hoc building site was gone, as was the Banksy kvetch-a-sketch and the large slab of wall on which it was lovingly deposited. Now we hear that said missing sliver of building has been listed in a Miami auction house with an estimated sale price of £320,000 to £452,000. For those of you who work in merchant banking, hedge funds or association football, I should explain that this is rather a lot of money. Especially for masonry. Personally, I would never pay more than a pound for a brick. And that's wholesale. I have to think of my margins when selling on. In fact, the most I ever got for a brick was £3.50, but that was during the London riots and if I had known that the excitable young chap who bought it was going to lob it through the window of Dixons, I would have advised him to think up another way of passing comment on the aforementioned tear-inducing modern life.

Mind you, who's to say said brick won't turn up in some US auction house in a sale of pseudo-revolutionary street weaponry? I'll start the bidding at a tenner…

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