In junior schools, girls could have found themselves over a headmaster’s knee for a spanking, but it would tend to be the younger ones. I only taught in all-boys schools. In the 1940 era, mixed schools at junior age were somewhat rare. I know one mixed school but here the headmaster did spank girls over his knee but never in the top juniors.
I think as we move into the 1960 era such things would be rarer still with older girls and indeed in junior school. Of course, we all know of the famous Dulwich College case. This proves it did go on but it was an unwise head that had even a ten-year-old girl over his knee for hand spanking.