"A levels"... it means the Escort in question has passed basic schooling exams and is capable of holding an intelligent conversation..
Some guys think it means that she "takes it up the arse", but this is considered rude and not allowed on these boards. You dont think "A" means that she "takes it up the arse" do ya?.... It wouldn't be a very good start for you here if you did ....
Go on ... ask me another one...