Jeremy Corbyn: To ask the Secretary of State for Defence what the cost to the public purse was in the current spending round of the maintenance of Trident and all aspects of preparation for its successor. 
Peter Luff: As stated in the White Paper ‘The Future of the United Kingdom’s Nuclear Deterrent’ (Cm 6994), published in December 2006, the costs of maintaining the UK’s nuclear deterrent are around 5% of the defence budget. This is expected to remain the case during the current comprehensive spending review (CSR) period, which covers the financial years 2011-12 to 2014-15.
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The assessment phase of the programme to replace the Vanguard class submarines started in February 2011 and will continue through to Main Gate approval in 2016. As noted in the parliamentary report ‘The United Kingdom’s Future Nuclear Deterrent: The Submarine Initial Gate’, published in May 2011, we expect to spend £3 billion on the assessment phase.
I am withholding further information on expenditure during the CSR period at this time, as this would be likely to prejudice commercial interests and the development of Government policy.
Jeremy Corbyn: To ask the Secretary of State for Defence whether the Trident Alternatives Review being conducted by his Department will consider alternative basing locations for the nuclear deterrent fleet. 
Nick Harvey: It will not.
As a separate point of clarification, the Trident Alternatives Review is led by officials in the Cabinet Office under my oversight, with support from the Ministry of Defence and other Departments.