yeah, got a vapour rise and it certainly is good but it is the venting capabilities that I'm referring to teclite and similar designs

Just wanted to say thank you very, very much everyone for all your helpful and informative advice. After weighing it all up I think i am going to go down the windshirt route possibly the Montane Jetsream as it is only 70g and has a full zip. This is probably a silly question, but if there isn't actually much wind, it is just plain cold, what sort of level of warmth does the windshirt add, is it equivalent to say a micro fleece?
Yours much less confused than I was!!

Far less than a micro-fleece - about the same as an ordinary shirt.

A windproof will kill the chilling effect of the wind. It adds a little warmth on it's own. Often thats all you need.
I've been comfortable with a base layer and a windproof when friends (windproofless!) were wearing many more layers to create the same comfort zone.
If the air temperature is pleasant but it's windy, then you don't need insulation, you just need to stop that windchill.
I used to carry a heavy 300 weight fleece but find a microfleece/windshirt combo warmer and more versatile.

Thank you again, that's helpful. Am going to order the jetstream today! Mike have you got yours yet, I found they were selling for £39.99 incl P&P at this site http://www.bikesyoulike.co.uk/ which seems reasonable.