Between the ages of 7 and 11 (1957 to 1961) I attended a mixed primary school where all the teachers used CP in one form or another, as did the headmistress. Between the ages of 11 and 17 (1961 to 1967) I attended a boys-only grammar school where about half the teachers used CP, as did the headmaster. In neither school was there the atmosphere of fear that you describe. The punishments were nearly always (although not universally) moderate.
Perhaps my two schools were unusual? They were in the north-west London, both state schools. I had some friends at other schools in the vicinity, and I don’t recall any of them being particularly scared of going to school.
Having attended schools in the same area (well perhaps 2 miles east – 645 as well as 660 trolleybus!) five or six years earlier than Alan, I have exactly the same recollection. At no time was there a climate of fear in either of my state primary or grammar schools.