Britain’s first motorway, the M1, opened on Monday 2nd November 1959 linking London and Birmingham.† Birmingham and Midland Motor Omnibus Company Limited (BMMO—Midland “Red” Motor Services) immediately took advantage of this by operating new high-speed “Motorway Express” services between London and Birmingham or Coventry. With inspired foresight, BMMO had especially re-engineered the BMMO C5 coach with a turbocharged engine, overdrive gearbox and rear toilet for these new services, becoming Britain’s first purpose built, and thus quite famous, motorway coach, the BMMO CM5T.
Although the BMMO CM5T is probably the most well known of all the BMMO built vehicles, it was basically no more than a modified type C5 coach. However, the success of the CM5T on the Motorway Express services necessitated the development of a larger, more powerful vehicle, and in 1963 a prototype for the BMMO CM6T entered service, designed and built specifically for high speed motorway work. Unlike the type CM5, there was never an equivalent non-motorway version, and the CM6T was not downgraded to bus work near the end of its life.
† In terms of strict historical accuracy, the M1 didn’t go to Birmingham, and at the time it opened came to a sudden halt in the middle of nowhere at Crick in Northamptonshire, roughly where the M6 to Birmingham now begins.
BMMO built the prototype CM6T in 1962, when the CM5 coaches were coming to towards the end of their service lives. Construction of the prototype was completed on the 12th September 1962, and the vehicle entered service at Birmingham (Digbeth) depot under the control of the experimental department on the 15th March 1963, with the fleet number 5295. Visually this vehicle was just a 36′ 0″ long version of the BMMO CM5, however it was fitted with a 10½-litre naturally aspirated engine, as opposed to the 8.028-litre turbocharged engine found in the CM5. The basic body structure was as per the BMMO S17 suitably fitted out for motorway duties with 46 coach seats and forced ventilation.
After a few months in service, the prototype returned to Central Works for modifications, with its David Brown five-speed overdrive gearbox being replaced by an SCG five-speed semi-automatic with direct-drive fifth ratio. The exterior and interior body was restyled with the lantern-style windscreen being removed and a curved version fitted. Seating was also reduced to forty-four. It is believed a turbocharged version of the 10½-litre engine was tried on this vehicle but abandoned as the naturally aspirated version had more than enough power to achieve 80mph on motorways. The top speed of the vehicle in turbocharged form is not known, but certainly 80mph was no problem on the non-turbo production vehicles.
The BMMO CM6 and CM6T production vehicles were completely restyled from the prototype, with a new six-bay body format that BMMO subsequently copied on all future designs. BMMO constructed twenty-nine examples at Central Works, and these entered service between February 1965 and May 1966. Twenty-four of these vehicles were built as type CM6T with forty-four seats and rear toilet (C44Ft), with the remaining five examples, fleet numbers 5667–5671, being built without toilet and forty-six seats (C46F) as type CM6. Other styling changes included the fitting of a peaked dome at the front and rear of the vehicle, which made for a very elegant vehicle when new in the red and black BMMO coach livery.
Mechanically the production version of the CM6T was the same as the final specification of the prototype with a 10½-litre naturally aspirated BMMO KL engine and a SCG five-speed semi-automatic gearbox, making the type CM6 unique in being the only BMMO designed vehicle fitted with this type of gearbox. The brakes were discs front and rear with a continuous charging system for the servo, unlike the type S17 that had the servo driven from the prop shaft and therefore had no assistance at all when stationary or travelling slowly. This was necessary as these vehicles were expected to run at 80mph on the then unrestricted motorways, so good brakes in all conditions were essential.
Many of the vehicles were allocated to Bearwood depot or Birmingham (Digbeth) depot in Birmingham, which ran many of the London services, with some going to Nuneaton depot for the Coventry to London services. The five CM6 vehicles were used on Service X43 and Service X44 between Worcester and Birmingham along the newly opened M5, and for most of their lives were based at Worcester (Padmore Street) depot.
Running only on Motorway Express services the type CM6 achieved unusually high mileage in a very short time and by May 1971 the first of the production vehicles, fleet number 5654, became due for overhaul. This vehicle was reclassified to type CM6A; having one-man operation equipment, power operated door, and a new larger bus style front dome fitted. Other modifications to 5654 included the removal of the toilet and wheel trims, and a repaint into all over red livery with the route indicators painted over at the sides. However for reasons unknown, 5654 was the only vehicle to be modified to type CM6A, spending a year operating the Service X43 and Service X44 from Worcester (Padmore Street) depot before the one-man operation equipment was removed and it was reallocated to other motorway work, reclassified to type CM6.
Of the remaining vehicles, at the time of overhaul several were stored never to run again, however the others were restyled with new additional bright work, re-trimmed seats, and large front domes similar to the type CM6A. Vehicles were also repainted into overall red bus livery, or later in to NBC “National White” livery. Restyling of this nature was unique to this class, but despite all this work the type CM6 had a very short life span and the Leyland Leopard type C14 coaches replaced the last examples of the BMMO CM6 on Motorway duties in April 1974.
The BMMO CM6 and CM6T was an extremely successful design but still had a very short service life compared with other BMMO vehicles. The high mileage was part of the reason for this, and certain unique parts became difficult to find after BMMO vehicle production ceased in 1970. A further issue was corrosion, as road spray containing salt was a major problem with these vehicles due to their heavy motorway mileages, and the CM6 had no more corrosion protection than other BMMO types, namely none at all! Taking all these factors together then CM6 was destined for a short life, and all of the type CM6 coaches were withdrawn with less than 10 years service.
Only a few examples found later service with other operators, with the remainder being sent to the breakers yard by the mid-1970s. However, two examples of the BMMO CM6T have survived and details of these can be found on the “BMMO CM6 - Preserved” page.
Certain information in the BMMO CM6 section was originally recorded by Arthur Homer, former body superintendent at BMMO’s Central Works. Special thanks to Arthur’s family for allowing us to use this unique information on this website. Other information in this section has been compiled by Mark Tunstall of the Worcester Bus Preservation Society.