By the mid-1930s, the BMMO network was expanding rapidly and the company were starting to run out of available service numbers. To free up numbers for new services, local area networks were renumbered with a prefix letter to represent the area when the network operated, so thus on Monday 7th January 1935 all local Malvern area services were renumbered in the range M10–M30 (with service number M13 being omitted for some reason. Unlucky?).
With the renumbering of local Malvern area services on Monday 7th January 1935, Service 370 running from Malvern Link to British Camp via Belmont, Great Malvern and Malvern Wells, became Service M10 for the full route, and Service M20 for short-workings.
Service M20 operated as a short-working variation to Service M10 between Great Malvern, Malvern Wells and British Camp only, from the introduction of the service in 1935 until it was withdrawn in 1940. Unlike Service M10 which continued to operate during the winter season on Sundays only, Service M20 ran only during the summer seasons.
See the Service M10 page more more details of the Service History for Service M20.
| M | 2 | 0 |
| July | 1938 | Great Malvern ↔ Malvern Wells ↔ British Camp |
Most pre-war summer season services did not return after the war, but Service M20 was one of the few exceptions. The service was reinstated over the pre-war route for the 1949 summer season, which ran from Saturday 7th May 1949 to Friday 30th September 1949, and again for the 1950 summer season from Saturday 6th May 1950.
Part-way through the 1950 season there was a general revision of services in the Malvern area and Service M20 was withdrawn on Saturday 1st July 1950.