That is a critical point, because the argument to which I have obliquely referred—I was tempted to refer to it more explicitly, but I decided not to, bearing in mind your stricture, Mr Stringer—and which is being put forward by civil service mandarins is not only that we should spend less, but that we should recognise the fact that we will only ever be involved in major conflicts along with allies and so we do not need the full spectrum of capability on land, at sea or in the air.
The problem with that approach is that it assumes that if we were to go into a conflict alongside allies at the beginning, those allies will remain available throughout—right until the end. What happens, however, if one of those allies is overrun and occupied, as has frequently happened in major conflicts in the past? If we are relying for the sake of our air power, for example, on a particular injection of expertise and capital from a particular ally who is no longer available, our defence capability could be fatally undermined.
I will conclude with this point. We are trying, as always, to construct a system for the air, as in the other dimensions, that is the most advanced the world has ever seen. That means that we have to be prepared not only to pay for it, but to recognise that we cannot expect to anticipate the context and circumstances under which the crisis will arise where the system will be put into action. We cannot anticipate that, so equally we cannot anticipate whether our allies who might be available in one type of conflict will be available in another and, even if they are available in that other context, whether they will remain available until the fight is brought to a close.
As we get involved in more complex and expensive systems—systems that take longer to design, develop and produce—we also must recognise the limitations on our scenario prediction ability. That is why we must invest enough and recognise that a full spectrum of military capability is essential, including, of course, in relation to the Tempest aircraft strategy.