Service 37A and Service 37B were introduced by Midland Red West Limited on Sunday 27th August 1989 as variations to their Service 37, which was part of the “Citibus†Worcester City minibus network. Both of the new variations ran over the same route as Service 37 between Worcester City Centre, Tunnel Hill and Warndon, but then Service 37A ran via Perdiswell and Blanquettes Estate on the return journey to the City Centre.
Service 37, Service 37A and Service 37B each ran with a 20-minute frequency during the daytime, interworked to give nine buses each hour over the City Centre, Tunnel Hill, and Warndon section of the route. Buses in the opposite direction ran as Service 34, Service 38A, and Service 36B, which must have made for a very confusing network.
On Saturday 9th February 1991 a group of new circular routes was introduced to service the new housing development at Warndon Villages. The new group of services were numbered in the range 39–41 & 43, and ran between the City Centre and Warndon via Tunnel Hill, so at this time Service 37A and Service 37B were withdrawn and replaced in part by Service 40 and Service 41 (towards City Centre), or Service 39 and Service 43 (towards Warndon for Warndon Villages). At the same time, Service 37 was reduced to run only between the City Centre and Warndon and was no longer a circular route with buses running in both directions via Tolladine Road and Tunnel Hill, and with the changes the overall frequency of buses running over Tunnel Hill was reduced to every 10-minutes.
1 Service 37A ran in one direction only with Service 38A operating over the same route in the opposite direction.