A comment that if Frank were to leave and be replaced by Zoe, Charlotte would be the perfect canditate for the 2IC position, got me thinking; within the current staff of doctors, who has seniority? IMHO, it goes Frank, Zoe, Charlotte (because she's been an ED registrar for at least six years - she makes a references to it in s5, even if she doesn't have her fellowship she still has loads more experience that Jack or Steve) (Jack/Steve) Bart. Before any Bart fans get upset, I've put him last because he's a resident and everyone else is a registrar at least.
It got me thinking, of Steve and Jack, who has seniority? They're both registrars, they've probably had similar experience in the ED. I'd be inclined to give Jack seniority because he has trauma and surgical experience and he's been in that particular hospital longer, but that's just me.
Anyone got an opinion?