I was on CID in Slough in 1979 . In those days CID officers dealt with ALL crime, that included shoplifters. The only time a uniformed officer would deal with a shoplifter is if he or she was a probationer and their tutor requested to take it for experience.
It was always very busy, we did spend a bit (well quite a bit) of time in the local pubs and betting shops though, chatting up informants you understand...
Things have certainly changed from what I hear these days. A lot of CID officers in those days had a job in CID for life, and they were good at it, they knew what was going on in their area, they knew the people you needed to know. Informants were dealt with on a much more informal basis, if you know what I mean..