When Birmingham and Midland Motor Omnibus Company Limited (BMMO—Midland “Red” Motor Services) were construction the final batch of BMMO S17 single-deck buses, three vehicles, built to identical mechanically and bodywork specification as the type S17, were used for development work, classified as BMMO S21A.
These vehicles each featured 48 coach seats with headrests, and having coach interiors they entered service in red and black BMMO coach lively. Seating was finished in a different colour scheme on each vehicle to gauge customer reaction for future build projects, and BMMO tested them extensively on long stage carriage services such as Service X91 running between Leicester, Coventry, Stratford-upon-Avon, Evesham, Worcester and Hereford.
All three vehicles entered service in January 1966 with DP48F layout and experimental seating as follows…
Built to BMMO S17 specification, all three of these vehicles were fitted with sliding windows, but in addition, 5723 was also fitted with roof mounted air scoops and forced ventilation through overhead luggage racks.
At the end of testing, BMMO concluded the most popular style to be the blue and grey seating used on 5724, and hence the company adopted that style as standard on their forthcoming BMMO S21. With testing completed, the three vehicles continued unaltered in service on long distance stage carriage services at the depots where they were tested.
After the introduction of the type S21, BMMO decided that the type S21A vehicles were more suited to long distance stage carriage work than to semi-coach work, which was the roll of the type S21. In December 1967, BMMO reclassified the type S21A vehicles to BMMO S22 inline with the class of dual-purpose bus that the company was constructing at the time.
In July 1970, BMMO downgraded the three type S21A vehicles, classified S22 by this time, to bus work. At this time, they received one-man operation equipment and reclassified to BMMO S17, then in 1973 and 1975, the company re-seated them with 52 bus seats. As with all S17 type, these extremely competent vehicles operated successfully and reliably throughout their lives, surviving until 1977 when they were withdrawn and scrapped.
Many Thanks to Mark Tunstall for providing much of the information on these pages.