Autocar published a review of the Fighter in 2005, in which they claim the car is an 'S', however EVO published a review in 2007 of the same car (same owner, Simon Draper) which specified the car in standard spec. I assume that the standard Fighter would be upgradable to 'S' specification, which might confuse the issue somewhat.
Bristol Fighter V10 S first drive review | Autocar
Bristol Fighter | Evo