Open the bonnet of a functioning, unmodified classic Mini and you will find a marvel of British automotive design. The A-Series engine was originally the work of Austin, a stand-alone manufacturer at the time but later submerged in the company which eventually became known as MG Rover.

The A-Series had a remarkably long life. It was introduced at a time when sugar, butter and meat were still subject to post-War rationing, yet you could buy a new car fitted with one ten years after the invention of the World Wide Web.

There were many changes in that time, of course, and no component of the final engine could be swapped with its equivalent from the first, but the basic design remained very similar throughout.

Many people were responsible for it, but the most famous was perhaps Harry Weslake, who designed the cylinder head. Among many other projects, Weslake was also closely involved with Jaguar’s early XK and V12 engines, and responsible for the Formula 1 unit which won the 1967 Belgian Grand Prix in the back of Dan Gurney’s Eagle. The little A-Series, designed more for economy than for performance, bore no resemblance to any of them, but Weslake was one of those engineers who could happily work on dramatically different projects.

As we’ll see, the Mini was by no means the only model to use the A-Series engine. In fact, it appeared in millions of small British mass-market cars, along with a similarly impressive number of kitcars and home-built specials.