Thanks to SteveB I had a known working MAF about 3 weeks ago now
Due to work, children, illness etc it took me a week to fit it (I did that because it was quicker than testing the wiring) but I didn't have time to prove it worked. The next morning I jumped in to the car to go to work and it wouldn't turn over - I just got a clunk from the starter and a dimming of the warning lights.
Battery went on to a smart charger and I left it for another week. Battery back in car on Monday (fully charged) and it still wouldn't turn over.
This afternoon I finally got 1/2 an hour to try and do some diagnosis.
After a few more attempts to start it (and much waggling of terminals) it suddenly sprang in to life. While poking around with a voltmeter trying to find a poor connection / high resistance I found a very hot cable crimp.
I guess that was the cause of the problem then
All I need to do now is find a good way to remake the joint (or acquire a good cable with terminals attached)
Ideas / tips anyone?