Need pictures of the receiver side with the safety on it and underneath the bolt on the socket. The rear sight is marked with a B so it might be a BSA-Shirley. Only Fazakerley and BSA-Shirley made the No. 5. Fazakerley made rifles from 1944-1947, BSA-Shirley from 1944-1946. Also look for a M/47C marking which would indicate a BSA rifle.
Nice looking rifle by the way.
TK