Thankyou for your collective input to my quiries in this regard.
I couldn't find anything in the current regs and I don't remember being told anything about this from when I got my license in '82.
I think it is clear that the main requirement is safety and airmanship based on the particular Aircrafts Flight Manual.
and Perhaps there's a little requirement on being ambidexturous too!
Personally, I like the RHS when in the circuit, especially for high wing AC.. quite simply, the view is better during the left hand turns imo.
Cheers
-flopter.