The 19 wasn't Midland Red, but was the Corporation's 'City Circle', and ran a circuit closer in than the 'Inner Circle' - it started on 2nd March 1932 and ran via Benacre Street, Bristol Street, Great Colmore Street, Cregoe Street, Granville Street, Broad Street, Sheepcote Street, St. Vincent Street, Summer Hill Street, Powell Street, Albion Street, Frederick Street, Vyse Street, Well Street, New John Street, Aston Road, Dartmouth Street, Lawley Street, Watery Lane, Adderley Street, High Street Bordesley, Alcester Street, Vaughton Street and Gooch Street.
From September 1939 it ran weekday peak hours only.
From July 1943 it was diverted from Benacre Street via Sherlock Street Gooch Street and Wrentham Street and from November 1959 it was diverted from Well Street via Barr Street and Great King Street. In 1964 it was further diverted from Well Street via Great Hampton Street, Hockley Street, Northampton Street and Warstone Lane to Frederick Street. I don't have a finishing date for it though.