Most approved schools (or community homes as they became in the early 70s) for both boys and girls are now featured on the Friends Reunited site, although most are not easily identifyable as being approved schools from the FR site.
Looking through the messages attached to these schools on FR I have yet to find a single reference to corporal punishment. Yet up until the 1970s these were schools where very formalised and often severe CP took place as matter of public record.
So this does seem to support the theory that people who were genuinely subject to punitive corporal punishment in their childhood would be reluctant to talk about it about it now. And that many of the CP references on FR or elsewhere on the Internet are probably either trivial, exaggerated or imaginary.