Following World War II, British airplane manufacturer Bristol received the designs of BMW’s 328 racing engine, among the most successful of the pre-war era, as war reparations.

Bristol took the engine, with its unusual dual pushrod-operated exhaust valves, and improved it for durability and reliability, then installed it in a new grand tourer with sensuously streamlined coachwork.

The original model, the 400, would spawn four further series with steadily improved chassis engineering and refined styling.

The 403, of 1953–55, featured an engine with larger valves and main bearings for 100 bhp and could accelerate from 0 to 60 mph in 13.4 seconds and reach a top speed of 104 mph.

Its chassis featured an anti-roll bar and improved Alfin drum brakes.

These luxurious, streamlined saloons were hand-built for the wealthy few and were thus always few in number.

Just 287 503s were made in the three seasons of production, and very few have made their way to the United States.

The example o...