Curious.
Just done me rocker cover gasket, and when putting the HT boots back on the (new) spark plugs, we noticed that Cyl no1 (from the left, looking from the front of the car) wasn't sitting on right. I'd not noticed this until today as I only got the engine cover off yesterday (legendary chocolate screws, innit?).
Cut the bottom off the boot, clip the lead back on properly, engine pulls more sweetly from low, low revs (ie just above idle, fourth/fifth gear, pulls happily from 15mph now, would previously grumble and labour) and generally seems a bit happier.
I'm thinking I might have found the cause of my fuel drinking problems.
new set of HT leads to be ordered from Ford tomorrow...will be brimming it tomorrow and seeing how it goes.