The second principle in determining our rates of tax is that we must bear in mind national needs, not only as regards what is essential but, to take the 1951 example quoted by the hon. Member for Gillingham, in terms of whether, at a particular time, because of some Crisis in Our Economy Or Some Difficult Period through which we are passing, we must, unfortunately, use the Purchase Tax as a deliberate weapon to damp down consumption of certain kinds of goods or, as in the particular case mentioned, to free particular commodities or raw materials for a rearmament drive or whatever else may be needed.