The fuselage was of square section and built around spruce longerons and ash frames, with internal wire bracing and fabric covering.

The third machine, G-ABAJ, was modified to take the 105 hp (78 kW) Armstrong Siddeley Genet Major engines as well as some other changes and became the prototype Westland Wessex.

Originally the prototype Westland IV and retained as a demonstrator, later converted to a Wessex and sold to Cobham Air Routes Ltd in 1935 and withdrawn from use in 1936.

Built as a Westland IV and registered as G-AAJI, originally intended for service in Kenya with Wilson's Airways but the order was never taken up.

G-ADEW – Westland serial number 1899, granted its certificate of airworthiness on 6 August 1930, sold to Sabena and registered as OO-AGF, then bought by Cobham in 1935.

G-ADFZ – Westland serial number 1900, granted its certificate of airworthiness on 30 August 1930, sold to Sabena and registered as OO-AGF, and bought by Cobham in 1935.