evidence indicates that one out of 3.5 aircraft fired from sites in Northern France would land in Greater London. This is an improvement on the figure of 1 in 5 on which previous calculations were based but it is not known whether this improvement is the result of a modification which would have to be incorporated in production models. (iv) Storage capacity of sites: The ski buildings, which are probably intended to store the weapon, would allow for approximately 20 aircraft to be stored on each site.