The engine on display is one of the marks of Merlin fitted to bomber aircraft. It is representative of all the Merlins used in bomber, fighter and reconnaissance aircraft, not only by the RAF but the USAF as well.
The Merlin is a direct descendant of the Kestrel engine, the power unit from the Hawker Hart and its many variants; an enlarged version of which powered the Supermarine S6 which won the Schneider Trophy for Britain in 1929. This led directly to the Spitfire aircraft powered by the new engine now called the Merlin. The first Merlin engine developed 880hp but by the time the last mark of Merlin was produced the power output was 2030hp. The Merlin engine was then enlarged still further and named the Griffon; it was used in Shackleton aircraft.
Aircraft which were powered by the Merlin engine include the Lancaster, Spitfire, Halifax, Hurricane, Battle, Defiant, Whitley, Mosquito, Hornet, York, Lincoln and North American Mustang.