Progress on this at last - but backwards
fitted a new stat and it boiled up as before.
replaced the water pump, but when i tried to refill the system from the expansion tank, it simply wouldn't flow into the engine, until i loosened the top hose at the pump end. It then flowed in niceley, i carried on filling till there were no more air bubbles coming from the loose hose then tightened it and manipulated the hoses till there were no bubbles appearing in the expansion bottle.
Ran it up, and guess what, IT EFFING BOILED UP AGAIN!!!!!
I've put a bunch of pictures of it on my blog, please have a look and tell me if you can see something obvious I've done wrong. Really, really fed up with it today.