The drug dealer thing, is just a possibility,of what nosy neighbours might think.
One client a day shouldn't be a problem, for how long a duration a booking is for.
If he gets awkward, just tell him to leave, if he refuses to budge, say you'll give him his money back.
Once his dressed just give him 20 pounds, not all of it, or threaten to call the police.
I did notice your transgender, so the chances are, he will be less reluctant, to be involved, if you mentioned the police, especially if his married.
Not 100% sure, but did hear a few years back, that no law has been enforced on transgender escorting.
Maybe someone from the admin team, might be able to clear things up on that matter.