Hi there
@rob evans , just a thought for you but when it next fails to start on the key with no error message on the dash give the gear selector a sharp slap forward with your hand and try again.
Then if that does not work as an alternative select neutral and try starting again.
I think your XYZ switch & cable are out of adjustment. Even if the key works and everything else is fine, if the car thinks it is not in
Park or
Neutral it wont spin over because this is a failsafe.
I had exactly the same issue with my car a few months ago. Even though it was showing as being in Park, and pushing the selector forwards would allow me to start.
I have since had the cable adjusted and the problem is gone.