New Service X51 was introduced by Midland Red (West) Limited on Monday 21st September 1981, to partly replace the historic Service X91 that had first been operated by Birmingham and Midland Motor Omnibus Company Limited (BMMO—Midland “Red” Motor Services) in 1929, and then by Midland Red Omnibus Company Limited (MROC) from 1974.
Two return journeys were operated each day, seven days a week, running between Great Malvern, Barnards Green, Malvern Link, Worcester, Pershore, Evesham and Stratford-upon-Avon. The section of Service X91 that ran between Hereford and Great Malvern was not replaced, and thus the new service did not enter the new Hereford trial area for deregulation of the bus industry, which started on the same date.
Between Great Malvern and Worcester, new Service X51 operated over the same route as Service 344 and to reduce costs it directly replaced certain journeys on that route, running at the same times as the withdrawn journeys. An evening return journey from Worcester to Pershore on Service 251 was also withdrawn and partly replace by a Service X51 journey, but only in one direction.
By April 1983, certain journeys of Service X51 had been rerouted between Pershore and Evesham to run via Pinvin, Wyre Piddle, Fladbury, Cropthorne and Charlton. Journeys that continued to run direct between Pershore and Evesham were renumbered to new Service X52.
Both Service X51 and Service X52 were withdrawn in 1986 with the deregulation of the bus industry.
| X | 5 | 1 |
| New September | 1981 | Great Malvern ↔ Worcester ↔ Evesham ↔ Stratford-upon-Avon | |
| July | 1984 | Great Malvern ↔ Worcester ↔ Evesham ↔ Stratford-upon-Avon |