Service B87 was introduced on Sunday 1st October 1939, as a tram replacement service, running the former tram route between Birmingham City Centre (Edmund Street), Oldbury, and Dudley (Birmingham Road).
The June 1940 timetable showed the full route (Service B87) operating with a frequency of “every 5 minutes” during the peak-time period, and “every 2 & 3 minutes” when combined with short-working variation Service B86, between Birmingham and Oldbury. By 1949, this had changed to simply read “at frequent intervals”. Unsurprisingly, Service B87 and it's short-working variations were one of BMMO's busiest route, and it was always operated using double-deck buses. For the introduction of these routes in 1939, BMMO allocated an entire batch of 50 new SOS “FEDD” double-deck buses (registration numbers: FHA 836–885) to Oldbury depot to cover the workload.
From it's introduction, Service B87 had terminated at Dudley Railway Station on Birmingham Road, which had been the terminus for the tram route. In 1952, the bus route was extended up Castle Hill to terminate at the new Bus Station on Fisher Street. Otherwise, the route for this service remained unchanged throughout it's history.
On Saturday 29th June 1968, Birmingham City Transport (BCT) closed their Rosebery Street depot, which had been responsible for their share of working on this group of routes. The work as moved to other depots, and for simplicity the ‘B’-prefix was dropped from the route numbers. Service B87 was renumbered to Service 87 at this time.
BMMO's operations on the Dudley Road services, including Service 87 workings, passed to West Midlands Passenger Transport Executive (WMPTE) on Monday 3rd December 1973, with the 1973 Transfer of Services and Assets to WMPTE. However, that would not be the last involvement by Midland Red on the route, as after deregulation, Midland Red West Limited would operate certain journeys from their Birmingham (Digbeth) depot, under contract from Centro.