XK

It's a testament to the design of the XK engine that it was last being fitted to a production car some 39 years after its debut. However, the XK doesn't rank among Jaguar's - and Britain's - most iconic engines for longevity alone.

Developed during the Second World War by William Lyons and his small team, the XK was Jaguar's first true in-house design. Featuring advanced features such as a twin overhead camshaft and hemispherical combustion chambers, the XK unit was among the most high-tech power plants of its day.

This put Jaguar in a fantastic position at the close of the war, with one of the highest specific output road-going engines around at their disposal.

The XK would debut in the XK120 Super Sports in 1948 - making it the fastest production car in the world - and was then fitted to the Mk VII saloon in 1950. In this initial 3.4 litre guise, the XK was rated at 160bhp and offered 195lb/ft of torque.

The XK would go on to be fitted to almost every Jaguar model of the next four decades, finding fame in icons such as the E-type, Mark 2 and XJ.