I recently got the chance to see Halas & Batchelor's 1945 film Handling Ships, which was directed, written and edited by Allan Crick, an animator with a naval background (although Denis Gifford's filmography identifies the directors as John Halas and Bob Privett). It's a bit of an oddity from a historical point of view: at seventy minutes long and predating Animal Farm by a decade it is technically Britain's first feature-length animated film. However, it was not intended for public viewing but for a specialist audience: the Admiralty. As the title suggests, Handling Ships is an instructional film about how to navigate sea vessels.
The film is primarily stop-motion, with a model ship manoeuvring a set, but there are a few bits of drawn animation. These are mainly diagrammatic, representing waves and currents, but the opening uses some trademark Halas & Batchelor character animation with anthropomorphic portrayals of the wind and tide.
For anyone who has no plans to manouver a ship any time soon, Handling Ships is one of those "for historical interest only" films; Animal Farm should remain the true beginning of British animated features. Handling Ships is undeniably a great example of instructional animation, however.
All images in this post are from a print purchased from the Imperial War Museum by an acquaintance. Go here for a full description of the license.