[Tony Williams]

Thanks George, interesting post.

The British certainly made use of upward-firing guns in WW1. The unsynchronised Lewis gun fitted on a Foster mount to the top wing of many fighters could be pulled downwards to enable the pilot to change the magazine. This action tilted the gun to point upwards. This was made use of by pilots to shoot upwards, especially when attacking airships.

The first 37mm COW gun installation, in a few DH.4 planes, was also upward-firing, but only a couple of these reached the front by the end of WW1.

Between the wars, the British issued a specification for fighters equipped with upward-firing 37mm guns, and two competing 'COW gun fighters' were built in 1931, by Vickers and Westland. Experiments with upward-firing Lewis guns fitted to Bulldog fighters went on in the mid-1930s.

Finally, in 1941 the British modified a Douglas Havoc to carry six remotely-controlled .303 MGs in a roof mounting: they were normally concealed by "upside-down bomb-bay" doors in the roof, and their angle of elevation could be altered between 30 and 50 degrees.

None of this experimentation led to any service use, however, except incidentally for the Defiant as you mentioned.