Re: Angels.
I think that's down to the BBC.
I can't remember the term being used to mean nurses, prior to the television programme in the mid seventies, set in the fictional St. Angela's in Battersea, and called Angels.
I agreee, it is rather disparaging.
I don't think many heavenly angels would do half the mucky jobs nurses have to deal with, for fear of getting their pristine wings dirty.