In 1916, the British Admiralty placed a contract with Frederick Sage & Co, a Peterborough-based woodworking company which had become an aircraft contractor for the Royal Navy, to design and build a primary trainer for the Royal Naval Air Service.

It was required to be robust, with a low landing speed and good visibility.

The resultant design, the Sage Type 3, was a two-bay tractor biplane powered by a Rolls-Royce Hawk engine.

In order to prevent the aircraft overturning during landing, it was fitted with an additional pair of wheels ahead of the mainwheels.

It proved to be slow, even for a trainer, and was modified with smaller tail surfaces and reduced weight, becoming the Type 3b (with the original design retrospectively designated Type 3a), which slightly improved performance.