For this role, the densest possible storage was required, so the initial design of a single booster rocket at the base end of the missile. This led to a very long design, as was the case for most contemporary designs, this was abandoned in favour of four smaller boosters wrapped around the fuselage, giving shorter overall length of about . The boosters were positioned so they lay within the diameter defined by the missile's wings, so they did not make it any larger in diameter when stored. If one of the boosters did not fire the thrust would be significantly off-axis, a possibility which was later addressed by moving the boosters forward so their exhaust was near the centre of gravity of the missile, allowing the missile's small control surfaces to remain effective. In contrast, the American Terrier missile was somewhat shorter at , but this required an additional tandem booster which took the overall length to .