no of launches for A&B/prof
The 'official' no of launches for those without a PPL was min of 19 launches plus 2 pre solo checks by another instructor.
That made 21 + 3 for the Proficiency badge and the BGA A&B cert. In fact there were no gliding badges then so Cadets were allowed to wear the BGA enamel 'two gulls' pin which was quite smart. If later one the managed some extended solo flights for the C then the '3 gull pin' could be worn.
What used to happen was the ab initio bit was sometimes added up incorrectly by the Cadet keeping the log and a quick couple of launches was required (after you had solo'd) to make it legal. This happened to me at SM. One had to be careful on the 'records' side if you had two 'Jones' or 'Smiths' on the same course.