Update Jan 2024. So previously the full clean of all electrical components throughout seemed to have solved the issue temporarily. There is now only one “permanent” error in the fault codes which is a gearbox sensor and is very costly to get at inside, and replace.
I suspect this was the cause of the intermittent fault when it either just stops whilst running e.g at a roundabout or in an stationary queue…and display says “gearbox not in neutral …service “ on the display.
The fault has not reoccurred for some months now even though the “gearbox sensor” is showing a “permanent” fault code and undeletable. It seems not worth spending £700 / £800 in labour and one sensor to replace it when the system has settled down, not caused a breakdown when running for some time…and has not caused a “fail to start” . If anyone knows of this fault and can offer advice or a solution at their garage or home visit mechanic at a reduced / lesser cost please let us know and we’ll consider getting it done to eliminate future stops.
The Peugeot garage suggests to leave it alone unless it causes a permanent breakdown and will not restart at all.