So it looks like the gearbox packed in today. Our local VW indie came across to pick it up. Good guys, I'm glad they are looking after it. He tells me that the gearbox is the achiles heel - built for an earlier model as a 4-speed it's not capable of taking the power from the gti engine.
So my luck may be in and I may be able to bag a used replacement or it can be re-built - on the other hand these gearboxes are rare and i may find myself with the alternative of either selling in it's current state or finding 2k for a new box (which would ultimately have the same problem).
We've a junior on the way so i've got some perspective on this

, but gutted all the same. New wheels, a fresh polish and it sailed it's mot on Monday - now this. Bugger.