Latest update: my dealer has checked the car all over and still can’t find anything wrong. The ECU is showing no error codes (as before). They took the car for a 50 mile spin and, of course, it performed flawlessly and they were not able to replicate the problem. Typical! The car is going to be returned to the factory tomorrow morning to see if they can work out what it is. Hopefully, Mark and his team will be able to sort it.