I got my new tail gate off a guy in Wales who had it on a new unused shell....paid the bargain price of £50 (5yrs ago now) for the tail gate suppose i should have asked how much for the whole lot

Yeah Turboshed...all the different major parts of a car carry a number in DVLA's eyes....tot up (ie use enough parts) enough of these numbers and its taken that enough of the original cars parts have been reused to warrant the reuse of its ID.