ZilchWoolham

Have seen them go for around £1500 - £2000 mark. But depends on model / colour / condition etc.
One going locally to me recently, started out at £2000 (which I didn't think it was worth)
ended up going down to £1500 but still didn't sell that quickly... went in the end, but don't know how much for
Put your offer in - they can only say no (if it's not too low - or you might get another phrase lol)
Good luck

Play it first. Some of the mid-70s Precisions were absolute dogs. Does it come with the original bridge and pickup covers? I"d say £1500 is reasonable if it plays well and is all original (aside from the changed pot), but make sure you give it a try first! 

Thanks for the replies! As it happens, I just found a 1972 Precision, and the seller is asking less than £2K. I've sent him a message asking whether it's all in original condition. Would I be correct to assume that the two years from '74 to '72 would be reflected in the price (albeit not to the same degree as the difference between a '72 and a '70)? The condition is a bit rougher, though, with some rather severe belt buckle rash (bare wood).