Well then here is a clue.
Renault F1, Driver linked to Renault F1
Prodrive Aston, Driver raced for Aston
Morgan LM Car, Driver for Factory LM Team.
The other driver I know of has not been recruited so top gear could show the car. Prodrive would only let the official drivers drive to car hence the stig has to be one of them. I know who it is as I have spoken with him on many an occasion.
TONIGHT They are showing the Britcar 24 at Silverstone.