OK, got a few more minutes this evening, printed out the relevant page of the wiring diagram and took it out to the car, and found that I'd got all the wires in the right place except one, which was in the hole that is supposed to be empty. So I moved it and hey presto, the car starts and runs fine just as it should. Thank goodness for wiring diagrams eh? Interestingly there are just two issues with the diagram of the ignition switch, one is that the diagram is drawn from the perspective of the front of the plug, so as you're looking at the back of the plug (where the coloured wires are) the drawing is effectively back-to-front. Easy enough once you've worked that out. The other issue is that all the wires matched in colour to those shown on the diagram except one, where the diagram showed a Green/Red wire, and on my car it's Yellow/White. However, as this was the only discrepancy it was pretty obvious where it should go, and so it proved.
So after a stressful afternoon I've achieved what I wanted to know, which is the right part number for the electrical part of the ignition switch! I shall now try and order that, at least fitting it will be a doddle after all this faffing around.
Cheers all
