Broomstick
I think you will find that most of this was documented in AICs many of which are probably difficult to find now as they have all expired. The AIS may well have a copies of old AICs but could charge you to locate them. There are still copies of CAP 53 and CAP 54 in existence which date back to 1989, these contained the licensing requirements at that time. Every pilot undergoing training had a copy.
The issue of remuneration is totally flawed, the law (ANO) says you must have a professional licence to be remunerated, yet many pre-JAR helicopter instructors still teach on a PPL [there was no BCPL(H)], and all microlight instructors teach on a PPL and invariably earn more money than a SEP instructor.