Parents hitting is always a problem subject because you don't know how hard. I think the restriction now is "don't use reasonable force"- what is reasonable force? You could argue a tap on the wrist is reasonable force.
I used to get smacked, slapped on the wrist, although I never got hit on the head. Ermm... I don't know. I wouldn't advise it myself, but then again, I think a lot of kids need a good slap nowadays... they have no respect whatsoever. I got smacked when I was a kid and it did me no harm at all.
A parent only has to give a little tap on the wrist and they get people in the street glaring at them as if they've just taken an axe to their head. This country is going mad...