>>>I am old enough to remember school desks that were entirely designed for right handed writers.
>
>Also scissors and specialist tools - even driving a screw has muscular/mechanical advantage for a right-hander.

A screwdriver is a completely symmetrical tool, so that leaves the screw. This would mean that lefties have some advantage when unscrewing, eh? Well, I beg to differ - the difficulty depends on many other factors, the direction of the thread being a distant fourth. I'm trying to practice both hands in as many applications as I can, and driving screws is where I'm pretty ambidextrous (writing... almost there, lacking speed, smooth moves and readability but got the rest :). I don't see that it's less handy on the left.