Corsa C 1.3 CDTI

[thug pug]

Hi all, I have the pleasure of trying to fix this Corsa that does not start when warm. The car will start first turn of the key when cold and runs without any problems or fault codes but just won't start when the engine is hot.
It has had elsewhere a new high pressure pump, fuel filter, battery and starter motor. I cannot see any signs of air getting into the diesel system.
Any help would be greatfully welcome.