Whilst boarding at LGW recently a guy came into the back galley, showed me his BAA airport ID, told me that he is a LGW based airport Fire Fighter and his seat number in case we needed his help.
He didn't wait around for a discussion, an upgrade, or any chit chat. He literally just told me what he did, where he was, and he was gone again.
I really appreciated it.
Would I upgrade him or treat him any differently? Absolutley not.
Was I grateful for his professionalism and courtesy? Absolutley yes I was.