In my day (mid '60s) the RAF would send a recruiter to our school but I don't recall the Army or Navy doing the same, however much later in life in the late '90s, a Navy Lynx called me up out of Yeovilton inbound to a school just south of Croydon. I asked if that would by any chance be 'Whitgift School' and they replied yes, so I mentioned I had a nephew who went there and was in the CCF. They tried to get me to reveal his name but I declined.