Yes It beggars belief. Maybe some sort of anger over the Tory ban? Or maybe just greed? Or once he did it once or twice he than was vulnerable to coercion and blackmail. But I think probably greed, a strange sense of "getting back" over the Tory ban and there it is. I probably, maybe, recognise the man from the days of Weller and Dufty in Birmingham? But never had any intercourse with him.
Regarding illegal "sales" I only had the one enquiry of that sort in all my near twenty years of holding a RFD. In the days before CLI (caller line indicator or caller display as it is also know). 'Phone rings and the question is asked
"Do you have spares for a Webley .455?"
"Yes," says I.
"Oh good. Only problem is it's "off ticket" is that OK?"
"And that's where this conversation ends." I replied.
And put the 'phone down.
But it wasn't unknown with some RFDs, apparently, anecdotally, in the Midlands in the 1970s.