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Trident

What people do is that they take all the existing running costs and project them forward for many years. The best estimates that we have of the actual costs of the design, manufacture, infrastructure and so on are the £15 billion to £20 billion estimates. We are somewhat strengthened in saying that, because the cost of the present Vanguard submarines—in today’s terms, not in the financial terms of the period in which they were built—is about £14 billion. We also have a lot of experience, not least in terms of the French system that is being brought into being.