From the Wikipedia page on the Griffon engine:
"Pilots who transitioned from the Merlin to the Griffon engine Spitfires soon discovered that, because the Griffon engine's propeller rotated in the opposite direction to that of the Merlin..."
I have that in another text too, which states that Griffon-engined spitfires handled very differently to the earlier marks, largely due to the opposite engine rotation.