Birds of prey are the namesake for the highly successful piston engines for Rolls-Royce aircrafts. After all, the aircraft engine production here exists to this day (2012), even the British government had to intervene occasionally. The type Merlin is particularly successful because it is found in the Second World War, in every second airplane of the Allies.
However, Rolls-Royce alone can not produce these quantities but receives assistance through the licensed construction at Packard. Of latter company is said to produce an even better quality version than thedeveloper company but this was partly also due to unskilled workers in the Rolls-Royce factories during the war. Civilian successor, a V-12 named Griffon.
For the Merlin engine, there is no specialization. It is used in all occurring aircrafts during the war, only for peacetime it seems to be less suitable because of its loudness. After all, he's up to the use of jet aircrafts still in competition with the radial engines.