I am pleased to say I was never in that position. Unless one is in a situation it is hard to say what one would do. It would depend on so many variables.
As a very broad outline, I would hope that the deputy head was female. This was common in mixed schools. That way a senior person in authorty could deal with pupils, while being of the same sex.
If this was not the case I would answer as follows
–in secondary school (ie after 11) I think it is wrong that men should punish girls. I also feel it would be morally wrong to make a girl of this age expose her bottom to a man.