curiouser and curiouser...
filter is as correct as possible-same as the one I'd put on at a previous service.
Pump was removed, overhauled, refitted, removed and checked when symptoms still the same, refitted, removed and checked again...at which point I said enough. I think I also said earlier in this thread that testing the pump 'unregulated' there is more than adequate pressure.
Anyway, onto todays puzzling development.
As suggested by Smaky I have just removed and cleaned the EGR valve, which was a bit sooty but all free and functioning, so fairly sure that is not an issue. So, disconnected the MAF to see if that made a difference. Needed easystart to begin combustion, but after that, as before, would rev to the redline while sitting still, so went for a quick blast. Well, gave it some beans out the end of my road-fine. Down onto the ring road-loads of beans, fine, cruise control light stayed on (my indication that it hasn't dropped into limp mode) and plenty of power. Next roundabout (about a mile) as I accelerated around it-cruise light out, limp mode, floored accelerator, cut out. Tried a few more times on the way back (about 1 minute!) cutting out again.
So....how did disconnecting the MAF fix it for one minute??????