[1] Like the Fairey Pintail,[2] it was designed to meet RAF Specification XXI, issued in May 1919 for an experimental amphibious aircraft that could operate from land, carrier decks or the sea.

In many regards, the Puffin was a conventional single-engined biplane of its day, but it had two unusual features: a single, central float (the first British aircraft with this seaplane configuration) and a vertical stabilizer and rudder mounted below the fuselage.

In the days of tailskid undercarriages for landplanes, such a layout could only be used by seaplanes with floats long enough to sit on the water almost in flying position with the tail well clear of the surface.

The tailplane was fixed to the upper longerons and carried a single elevator surface, mounted on off-set hinges to provide aerodynamic balance.

The gunner behind him, whose need for an excellent field of fire had determined the tail arrangement, had the standard Scarff ring mounted Lewis gun of the time.

[1] The Puffin was powered by a 450 hp (336 kW) geared down Napier Lion II engine,[1] a 12-cylinder unit with three banks of four cylinders in W or broad arrow arrangement.

The wheels were linked by an axle that rode in a vertical slot in the float at its deepest point, and a hand driven screw enabled them to be raised or lowered.

[1] Three Puffins were built, the first made its maiden flight from the Marine and Armament Experimental Establishment at the Isle of Grain in the hands of Norman Macmillan on 19 November 1920.