The Volvo Ailsa B55 was a front-engined double-decker bus chassis built in Scotland by Ailsa, Volvo's British commercial vehicle agency. It was in production from 1973 to 1985, and was a relatively successful alternative to the ubiquitous rear-engined Bristol VR, Leyland Atlantean and Daimler/Leyland Fleetline of the period.

The vehicle first appeared at the 1973 Scottish Motor Show, and was well received.

Versions: The chassis was designed with a front mounted engine that still allowed a front entrance position suitable for one-person operation. In this sense there was a common goal with the earlier, unsuccessful, Guy Wulfrunian. The engine was the Volvo TD70, a compact turbocharged unit of 6.7-litres. The rest of the design was relatively simple, with beam axles and leaf springs. A Self-Changing Gears semi-automatic gearbox was used.

A prototype lowheight Ailsa, designated B55-20 (instead of the standard B55-10), was delivered to Derby Borough Transport in 1977. It remained a one-off and is now owned by WJC Coaches in Scotland.

In 1977 an improved MkII version appeared, with two transmission options offered - a Self-Changing Gears pneumocyclic unit and a Voith D851 with retarder. It was followed in 1980 by a MkIII version, for which the Ailsa name was dropped. This continued to use the Volvo TD70H turbocharged engine, and utilized a Volvo truck rear axle in place of the previous troublesome axle. Air suspension was also an available option.

In 1981, a 3-axle version of Ailsa B55 was developed to meet the demand of 3-axle buses in Hong Kong. (kilde: Wikipedia)