It was an extremely advanced design for the era,[1] using a nine-stage axial compressor, annular combustor, and a two-stage turbine.

In the post-war era, newer engine designs provided much higher performance, and interest in the F.2 waned.

His partner, Hayne Constant, started discussions in 1937 with Manchester-based Metrovick, a maker of steam turbines, to produce the new machinery.

Incidentally, Metrovick had recently merged with British Thomson-Houston, another turbine builder who were supporting Whittle's efforts.

In April 1939, Whittle gave a startling demonstration of his experimental engine, the WU, running it for 20 minutes at high power.

Metrovick's head of design, David Smith, decided to end development of the turboprop concepts and focus on pure-jets instead.

In July 1940 the RAE signed a contract with Metrovick to build a flight-quality pure-turbojet engine based on the Freda turbine.

The design cleared its special-category flight-tests in 1942, and flew for the first time on 29 June 1943 in the open bomb bay of an Avro Lancaster.

Compared to the centrifugal-flow Whittle designs, the F.1 was extremely advanced, using a nine-stage axial compressor, annular combustion chamber, and a two-stage turbine.

By that time, there were a number of engines in development based on the Whittle concept, but the F.2 looked considerably more capable than any of them.

[6] To address these problems, in August 1942 a minor redesign delivered the F.2/2, which changed the turbine material from Rex 75 to Nimonic 75, and lengthened the combustion chamber by 6 inches (150 mm).

Development of the F.2 continued on a version using a ten-stage compressor for additional airflow driven by a single stage turbine.

[7][1] The new F.2/4 - the Beryl - initially developed 3,250 lbf (14.5 kN) and was test flown in Avro Lancaster Mk.II s/n LL735 before being installed in the Saunders-Roe SR.A/1 flying boat fighter.

Nevertheless, later on a Beryl from the SR.A/1 prototype was removed and used by Donald Campbell for early runs in his famous 1955 Bluebird K7 hydroplane in which he set seven water speed records between 1955 and 1964.

A bonus was a marked decrease in noise levels which resulted from the slower, cold air from the fan mixing with the fast, hot exhaust from the gas generator.

Following on where the F.3 left off, the F.5 was a version of the F.2/4 with an open rotor (unducted) thrust augmenter added to the end of the jet pipe, somewhat remote from the HP turbine The 5 ft 6 in diameter fixed pitch propellers, which contra-rotated, were driven by a four-stage statorless LP turbine unit, similar to that of the F.3.

Design features of the Metrovick line were worked into Armstrong Siddeley's own line of axial compressor turboprops, although Armstrong Siddeley dropped Metrovick's use of gemstone names for their engines in favour of continuing with animal names, in particular snakes.