The standard Midland Red single-decker of the late fifties was the 44-seat S14. There was a need for a dual purpose version, seating 40, for the company's longer services across the Midlands and to assist the coach fleet at busy times. The company thus designed the S15 of which nearly 100 were produced in two batches in 1957 and 1962. They were graced by the black roof which denoted the company's coach fleet. Apart from their internal refinements, hopper ventilators and essential luggage compartment, the mechanical design was beefed up with twin instead of the single rear wheels that had been an unusual feature of the S14. The 1962 S15s were the last 30 feet long single-deckers built by the company as 36 feet long buses were now permitted.

5073 entered service from Shrewsbury garage in November 1962 and typically worked the long X96 service via Birmingham to Northampton. The S15s were later displaced by newer, bigger vehicles on such routes and relegated to ordinary services, 5073 receiving conventional bus seats in 1969. It accumulated 418,000 miles and became the last active S15 with Midland Red. 5073 passed to a private owner in September 1974 and acquired by Wythall in 1977. In recent years it has enjoyed a major mechanical and body overhaul but still carries standard bus seats until the original style can be sourced or manufactured.