To ask the Prime Minister, pursuant to the oral answer of 1 December, Official Report, column 761, if she will give a detailed breakdown of the statistical evidence on which she based her statement about the comparison between Trident, Polaris and the Soviet Union's nuclear forces; why she chose 1970 as the baseline; and if she will make a statement.
The answer I gave referred to strategic nuclear warheads. The first part of the comparison assumed 192 United Kingdom Polaris warheads and approximately 1,800 Soviet strategic warheads. The Trident part of the comparison assumed a maximum of 512 United Kingdom Trident warheads and 6,000 Soviet strategic warheads. The figures give ratios of 11 per cent. and 9 per cent. respectively. 1970 was used as a convenient baseline because this was the year in which the fourth United Kingdom Polaris submarine first became operational.