Ok fitted a replacement metering head/fuel distributor today and the car kept starting idling for a few seconds then cutting out. Tried starting with and without the cold start valve plugged in, pushing the air flap down neither of which appeared to make much of a difference.
Removed all the plugs cleaned them up and it started struggled to hold the revs and unless I opened the throttle it would again just cut out.

Eventually it started to idle correctly and was ok, now I'm not sure if it was being problematic due to being stood over the last week and the fuel system not being primed/bled but I do have my doubts as to whether or not the metering head was the true cause of my problems prior to me breaking the old one.

Hopefully it will start again fine this afternoon and give me no more trouble otherwise it is going to require looking into further to find the true fault.