...Anyway, if you look at the ops profile, it seems he's been working in London fitting gas meters - if this is the case then he must surely have some gas qualifications...
He may have
somequalifications, but that does not make him a RGI.
He could well have core and meters, but not necessarily boilers. Even if he does, if he is working for a company under the company registration, it would be illegal to do jobs on the side.
You are a RGI when YOU are registered, not the company you work for. The very reason for having to work under supervision before becoming registered in your own right is lack of experience, like the op seems to display.