Vacuum advance is running of ported vacuum from the carb body. I'm confident distributor advance (mechanical and vacuum) is working well. I've actually slightly increased total mechanical advance (just a few degrees) by filing out distributor weights slightly. It's just the original distributor, but it's in good (however no longer original) condition.

Thanks sss. I'll do as you suggested. I've played around with this before, but only while under the bonnet. I've never driven the car with the acc. pump disengaged. I'm guessing it will suggest acc. pump not fully contributing, but will be worthwhile all the same. I'll post results when I get around to it.

So you think it's worthwhile removing the bridge in the manifold hey? I guess it can't hurt (I don't think..) and it does make sense intuitively.