RR - the REC is a trade association only, with limited (and no legal) powers. The government should police the industry under the Employment Agencies Act, but does little/nothing except worry about gangmasters.
I've been recruiting for 25 years, had one visit from the govt. inspector (when we had to have annual licences, pre-about 1995) and nothing since. I'm not a member of REC, either. But I stay well within the law, and am only an agency in name. I'm not in the aviation sector, however.