Hot start problem

[hector]

After a decent run ie. car up to normal running temp,and engine is stopped,er like for petrol the engine will not restart - major embarassment/who's the ****er in the TVR? Every thing is normal on attempting to restart, except that on turning the ignition key to the final position there is nothing, there is no response from the starter motor. After waiting a while, 20 minutes or so, the car starts as normal and runs ok. I am going back to the dealer but he has no idea what is the matter. Please respond with your thoughts. Maximum grin factor until it needs fuel.