Extract from - British Bomb and Rocket Pistols and Fuzes.

“The No. 34 fuze was originally designed for use in a 450 lb AP bomb development of which began in 1924. The main requirement for the fuze was that it should provide a delay equivalent to 50/16m travel after striking ¾ inch steel plate at 700 ft per second. The design proposed was for a vane-armed tail fuze with a pyrotechnic delay and a primary detonator maintained out-of-line with an inertia pellet until the fuze armed. The rotation of the arming vanes unscrewed an arming spindle from the inertia pellet and allowing the primary detonator shutter to rotate in alignment with the explosive train. On impact the inertia pellet flew forward to initiate the primary detonator, the flash from which ignited the delay train; this in turn initiated the main detonator. During development it was decided to incorporate a reduction gear on the arming vane to ensure a safe separation from the release aircraft before the fuze became armed. The fuze was extremely sensitive to vibration.

Further protracted development trials ensued and were not completed until June 1930, but production of the Fuze was delayed until the following December to await manufacture of the bombs. Very few Fuzes had been produced by July 1932 when production of the 450 lb AP was cancelled and with it, the requirement for the No. 34 Fuze.”