And you really need to read up on what constitutes original research. This is certainly not it. I think you may be misunderstanding the information that is being provided. These are posts previously held by the characters during their on-screen time, not posts in their back-stories which have not actually been shown on screen (as a long-running show, characters have frequently changed jobs or been promoted). As a TV programme, Casualty is media in itself and therefore a reference in its own right. If these characters previously held the posts listed in the show then the show is the reference, just as their current posts are referenced purely from within the show. 