THOUGH Bagehot is a hand-wringing liberal on lotsof topics, when it comes to dodgy public art (taxpayer moneyed or no) he is a raving conservative. One of the less delighted surprises of returning to London after a long stint abroad hasactually been the discovery, street by street, of 13 years’ worth of duff setups. So I cheered a piece in the mostcurrent Spectator by Richard Dorment, art critic of the Daily Telegraph, denounc