[1] Avro's design, the Type 555 Bison, was a two-bay biplane, powered, like the Blackburn, by a Napier Lion engine.

An enclosed cabin with large rectangular windows on each side housed the navigator and radio operator and all their equipment, with sufficient headroom to stand upright, while a cockpit for a gunner armed with a Lewis gun on a Scarff ring was provided in the rear fuselage.

[2][3] The aircraft had handling problems, however, caused by interference of the pilots cockpit with the airflow over the upper wing.

[4] A Bison I was fitted with floats and retractable wheels but tests proved the design was not suitable for seaborne use.

[5] Although designed for a naval requirement the first deliveries were to the Royal Air Force in 1922 to replace the Westland Walrus for coastal reconnaissance work with No.