The British Rail Class 22, originally designated the North British Type 2 diesel-hydraulic, was a small class of medium-power locomotives built for the Western Region of British Railways during the period when British Rail experimented with multiple traction types. Conceived under the Modernisation Plan, the Class 22 combined a compact body and a hydraulic transmission intended to offer a favourable power-to-weight ratio for mixed-traffic and secondary duties. Their external styling and compact, somewhat boxy appearance led to the popular nickname "Baby Warship" because of a resemblance to the larger Warship-class diesel-hydraulics.
Design and technical characteristics
Class 22s were Type 2 locomotives intended for local passenger and freight workings where a moderate axleload and flexibility were useful. Unlike contemporary diesel-electric classes, they used hydraulic transmission, an approach favoured by the Western Region at that time because of perceived advantages in certain power ranges. Visually they shared cues with other contemporary designs and could be confused with the superficially similar Class 21 diesel-electrics; for contrasts in transmission and equipment see Class 21. For background on the hydraulic approach see diesel-hydraulic and broader entries on diesel-hydraulic locomotives.
Operation and service history
Introduced onto secondary routes, branch lines and local services, these locomotives worked mixed-traffic duties where their compact form and hydraulic transmission were acceptable. Operational experience was mixed: while hydraulic transmissions provided good acceleration and a favourable weight distribution in some roles, they could be more complicated to maintain within the wider British Rail fleet, which increasingly favoured diesel-electric standardisation for ease of maintenance and operational commonality.
Withdrawal and legacy
As British Rail pursued fleet standardisation and as maintenance costs and interoperability concerns grew, the class had a relatively short service life compared with many diesel-electric types. Most units were withdrawn and disposed of; the class is often cited in studies of mid-20th-century British traction policy as an example of regional experimentation with differing technologies. The manufacturer, the North British Locomotive Company, is discussed further at North British Locomotive Company.
Historical interest
- The informal name "Baby Warship" reflects stylistic links to larger Western Region diesel-hydraulics rather than identical mechanical design.
- Comparisons with the Class 21 and larger Warship types illustrate the trade-offs between hydraulic and electric transmission philosophies.
- Although no large-scale preservation legacy exists for the class, it remains of interest to historians and modellers studying the transition from steam and the regional choices made during the Modernisation era.
The Class 22 therefore represents a compact chapter in British postwar railway history: a deliberate regional experiment whose operational realities helped shape subsequent decisions about traction standardisation and fleet planning.