No post, whatever the industry, should be filled just to tick a diversity box.
I have a very narrow music taste, being Soul and Funk only, and Craig Charles, who clearly knows his subject, has a brilliant show on Saturday evening on 6 Music, and if he was replaced by a woman simply to tick a box I'd be furious.
Filling posts for me is all about merit and the ability to do the job. If that meant that an authority on my type of music was a one armed Chinese lesbian pygmy, I'd be happy with that, but I wouldn't be happy if, for example (as gorgeous as she is) Fearne Cotton got the job (this assumes she's not an authority).
I have no idea who Paul Jones is, but he sounds like an authority, and therefore should be retained on merit alone, surely?