Our lecturer quoted "never strike a child except in anger......and then strike to kill"

An exageration obviously, and talking about school age children and teachers not parents. I think his point was that hurting children should be seen by both teacher and child should be seen as loss of control, not a cold blooded punishment. Or maybe just don't do it.

Watching wildlife films, you see animals cuffing their young. Preverbal children are could be seen as young animals, physical controls are needed - restraint where neccessary as well as lots of cuddles.

A study of child rearing in Sheffield found that parents who used smacking tended to need to escalate the punishment to get a result, and what some called a "tap" was quite severe.

So maybe a law stating that this is not acceptable is good, but it needs to be sensibly interpretted.