The hon. Gentleman must understand that the Minister of Defence, like the Air Staff, must calculate what sort of weapons we may be up against in five, 10 or even 15 years' time. We are now talking about a weapon which does not even come into service until 1969, but which must remain an effective weapon for at least 10 years after it has come into service. I recall that the hon. Gentleman suggested the other day that we could do this reconnaissance work with missiles.