I'm doing some research on court procedures during the '20's and '30's in England. I understand that at that time there was a Director of Public Prosecutions, and some of the resources I have found suggest that the Treasury Solicitor was actually responsible for the prosecution itself. Any information or references would help, but I'm particularly interested in who actually handled the prosecution at trial. Was there a permanent staff of lawyers (presumably barristers), or were they selected on a case-by-case basis?
I believe that it wasn't until fairly recently that the Crown Prosecution Service took over most prosecutions. It is highly likely that prior to this point, but after the establishment of police forces, the Police were responsible for prosecutions; though whether it was individual officers who made the relevant arrests, or specialists within a Force, I have no idea. Certainly hints in that direction are given by the CPS history on their own website; to quote briefly:
1962 A Royal Commission on the police said that it was not acceptable for the police to use the same officers to investigate and prosecute cases.