For "fastest British car" it has been taken apart many times - not least the Ford RS200 (which could be geared for 0-62mph in 3.06s OR a top speed of 206mph), the Jaguar XJ220 (214mph), the Jaguar XJR-15 (200mph), the current Jaguar XKR-R and S-Type R (both limited to 155mph, but capable of 185mph without the limiter), the Aston Martin V8 Vantage (200mph), the Aston Martin DB7 (185mph), the Aston Martin DB9 (195mph), the Aston Martin Vanquish and Vanquish S (199mph) and, the daddy of them all, the McLaren F1 (a meagre 241mph).
The Lotus Carlton WAS the world's fastest production 4-door saloon car. However, Brabus took this a while ago with a variety of cars.