The OCS also claimed that “most of Britain’s difficulties apparently centred on developing the maneuvering bus, which was the most technically complex component of the system (and which Britain eventually hired US contractors to build)”. I have no information on whether this is correct or not.

From the information that I have, the first bus maneuvering concept was powered by jets of gas metered down from a single very high pressure compressed gas bottle (stainless steel sphere). This was because the RN initially totally refused to have Hydrazine on their boats. The high pressure gas system worked well in the vacuum chamber but flew very badly on test shots. Crises erupted, so a team of consultants from an American company was brought in to review the design. The outcome of this was replacement of the compressed gas system with a more conventional Hydrazine decomposition system. The Amercian company became the prime for the bus reaction subsysystem development and the RN was persuaded against their better judgement (at government level) to reverse their original edict.