Thanks guys for all the input. I don't mind replacing stuff on this car, I just want to replace the right part that causing the problem. I guess I'm convinced it's unlikely the trigger points are the big problem. my plan is to clean then up as best I can, perhaps bend them a little to account for cam lobe wear and re-install them. If the car then fires up and runs like a top I'll know it did have something to do with them, if not I'm back to square one. I'll go back through and clean every connection I can find that has anything to do with engine operation. There are those manifold pressure sensors and air sensors and temperature sensors, etc etc. I suppose it could be a problem with anyone of them!
Thanks for the tip regarding Boston Volvo, I'll keep that phone number. I am aware of A.C. Wheeler in Leeds, I just have never made it there. I'm sort of stubborn in that I like to try to fix everything myself (sometimes to my and the cars detriment!). This one's a little tough as thankfully I have it at home but I also can't drive it anywhere for expert help.
George: The electronic ignition is all original, when I look at these early components, I sometimes wish for the newer stuff. As much as I love this car I can help but envy my sons trouble free operation of his Chevrolet system!
I guess I'm off to bust some knuckles. Please keep the advice coming, especially which componenets I should focus on....Cheers