[1] It was a way of producing an all-metal aircraft with an airframe built up from simple, non-machined metal shapes, covered by very thin 0.4 millimetres (0.016 in) corrugated light alloy sheets.

[2] The Vireo (named after a Latin word thought to mean Greenfinch) was built to Air Ministry specification 17/25, intended to evaluate both all-metal aircraft and low powered, catapult launched, carrier borne fighters.

The flying surfaces were all without external bracing; the wing was tapered, of deep section and incorporated twin machine guns.

[2] The Vireo was powered by an uncowled 230 horsepower (170 kW) Armstrong Siddeley Lynx IV radial engine, driving a two-bladed propeller.

[2] The Air Ministry's interest in low-powered on-board fighters, catapult-launched to compensate for their small engines, waned when the Vireo proved no faster than the conventional ship board aircraft like the Fairey IIIF.