However after a 300mile round trip and a morning at Hdi-Tuning in Bristol I can report that the car is actually cured.

I am a bit smug because while various vehicle techs have offered me some utterly rediculous suggestions over the years I had long since believed it was shite software.
Steve at Hdi ran all the usual diagnostics while I drove, a few tweaks to no avail then tried a different software version, Bingo (Berlingo), totally different.
A few more tweaks, a St1 remap and the old girl is like a new car, also moves rather like the Starship Enterprise on a shout.
Slight downside is the Berlingo software it's now running on doesn't talk to the fuel computer, so no MPG computer. Range function still works though.
