The Taurus wasnt reliable enough so a non started for a Hurricane rival.
It was used on the Gloster twin, and whilst the Taurus TE/1 (with which it reached 360 mph at 15,200 ft.) did give problems - even the IIIs derated to 900 hp reached 332 mph. But that maybe makes the case for retaining Mercurys but more powerful ones.
The Venom was good. 312mph on 625bhp is very good. Available in 1936. Proper job. Even with full kit I bet it still would have been a better bet than a Gladiator.
Gladiator had a 830bhp Mercury radial and just cracked 250mph. Had a Venom had the Mercury then it would have seemed like a rocket ship.
Glad had 840 hp Mercury, Venom + Mercury, would have needed structural changes to cope with the centre of gravity with the heavier engine.
100 octane fuel and a constant speed propeller and it would have been at least on a performance par with a Hurricane.
Why did Vickers use the Aquilla when the Mercury was available and increasing in power and flying? The Venom may have been too small for the physically heavier and bigger Mercury...but maybe design for the Mercury in first place.
The point is here surely that it was designed to get the best out of that low power, by having a small light aircraft, if it was designed with a Mercury doubt it would be any better than the Gloster.
The Gloster F5/34 first flew in 1938 and was no where near fast enough. just too late. I wish it first flew in 1936 and it may have gone into production although I doubt it. The RAF and the British Air Ministy didnt believe in radials until the Fw 190 showed them the errors of that philosphy.
Earlier biplanes mostly had radials, the Ministry I don't think had any bias against them, it was just that the Merlin was more efficient than the radials available at the time. There were problems with the Hercules - Mercury stayed in production as a result, yet the Boulton-Paul P.88a coulld so easily have had a life, instead of being stillborn! And seems a difference of the Gloster first flight, Wiki says Dec '37, but LFE Coombs says Dec '36, and it was a Mercury IX 840 hp.
An American engine? Licence built? When we still had an engine industry? No thanks!