It’s definitely not the EGR as we had that with the last one.
However... I’m glad to say I’ve fixed it today.
Disconnected the battery for a few minutes to reset the ECU then followed the procedure to retrain the idle etc, which is as follows:
1. Turn the ignition so it’s on and wait two seconds before starting the car - make sure that everything electrical like the headunit / climate etc is off before you do the latter.
2. Raise the revs to around 3k and hold them until the radiator fan kicks in.
3. Let the car idle for five minutes. If the fan kicks in, don’t count any of the time it runs as part of the five minutes.
And that’s it.
Before I did this, if you were driving along, dipped the clutch then released the throttle and the revs straight dropped down to idle.
Now, if you’re quick with the clutch the revs will rise slightly before dropping - in other words, the same as a GE but far less of it, so about right actually.
Then, when the revs drop, they seem to fall off a little slower and pause briefly at 1k RPM before dropping to idle.
Net result is a smoother gear change. Pulling away is now as it should be so this hasn’t just made adjustments for idling - the car is now obviously maintaining the revs applied when using light throttle to pull away far better than it was before.
Also smoother on and off when doing a bit of stop start in traffic.
So I is a happy bunny once more and to the point I used some of the time I expected to be still stood by the car scratching my head well - resprayed the wheels (matt black, nice contrast to the metallic grey bodywork) and buffed up the headlight lenses as, like me, they were a bit dull.