Gus -- you have it backward -- the early Spits had Merlins & the later spits had Griffons -- the Mk XIV was the definitive wartime Griffon powered Spit. The only early Griffon powered Spit was the MkIV -- which was the prototype for the Mk XIV. Also, some of the later Spits were still Merlin powered -- Mk XVI, for example.

Khodges -- you said "why do aircraft engines turn clockwise --?", not why do some, or why do most most. If you want more examples of left hand rotation -- Chipmunk, Tiger moth, Firefly, Gipsy Moth -- there are lots more.

Left hand rotation is/was more common in Europe. Most US engines turn clockwise, & today, the market in prop-driven a/c is dominated by Canadian & US powerplants, & US propeller manufacturers -- therefore clockwise rotation.