More grain-o-cam photos now...just the one on my phone which IIRC is 3.2 pixels. I keep forgetting to take a decent camera up to the workshop.
The filler neck has now been assembled, not forgetting the O ring between the neck and locking ring (I did forget the rubber gasket between locking ring and bodywork, which was annoying).
Then mounted it on the tank - it is possible to fit without dropping the auxiliary tank, but a bit of a fiddle. The captive nuts on the neck had long since rusted away as they are in constant contact with the stainless screws which Citroen used. I'd handily had 3 stainless UNC allen screws knocking around in the cupholder of the Focus for months, which were coarse enough to cut their own thread in the plastic.
And finally, fitted the flap itself:
The colour is a pretty good match to the rest of the wing, at least in the light levels I was working at. I should probably respray the flap too, to get rid of that scratch which has been there for at least the last 9 years
The bumper is now back on too, and so are the rear lights although the reversing lights seem to have stopped working. Not sure whether that's now an MOT fail, but I have tomorrow evening to sort that. As well as fixing on the wing trim strip, and the lower wheel arch plastic guards which I've also sprayed.