The Department does not cost the safeguarding and security of individual capabilities. Given the multi-layered make up of security arrangements protecting the deterrent, overlapping with those of wider defence personnel and capabilities, identifying accurate costs could be achieved only at disproportionate cost.

The in-service costs of the UK's nuclear deterrent, including the costs of safeguarding, is estimated to be around six per cent of the annual defence budget.

Further to the Strategic Defence and Security Review 2015, we are investing an additional £642 million in the design of the Successor submarine and ordering additional long-lead items, including for the fourth submarine. Negotiations with industry remain on-going on options for the subsequent investment stages and their scope, time and cost. The 2016 Annual Update to Parliament, which sets out progress on the Successor submarine programme, is planned for later this year.

Can the Minister confirm that the last Government looked at all the alternatives to our continuous at-sea nuclear deterrent, and that none offered the protection that we need? Does he agree with the two former Labour Defence Secretaries who have said that it is

“self-evident that a British nuclear deterrent will be essential to our security for decades to come”?

The nuclear deterrent is the cornerstone of the UK’s defence security policy. Maintaining the UK’s defence nuclear enterprise supports over 30,000 jobs across the UK and makes a significant contribution to the economy.

In the UK, four key suppliers directly support the delivery of the Trident programme. The Atomic Weapons Establishment (AWE) managed and operated by AWE Management Limited is based in Aldermaston and Burghfield; BAE Systems Maritime-Submarines at Barrow-in-Furness; Babcock at Devonport; and Rolls-Royce at Raynesway, Derby. There are thousands of jobs sustained across these sites.

There are also 6,800 Ministry of Defence (MOD) civilian and Royal Navy jobs at Her Majesty’s Naval Base Clyde including contractors from Babcock, Lockheed Martin UK and Rolls-Royce. This figure is due to grow to 8,200 in the 2020s. Rolls-Royce also operate the site at the Vulcan Naval Reactor Test Establishment, Dounreay, supporting the Trident programme and other nuclear-powered submarines. Also the Defence Equipment and Support’s military and defence civilian personnel are based at MOD Abbey Wood and other sites in the UK.

The ability of these key areas to deliver their programmes depends heavily on an extensive network of sub-contractors who are working indirectly in support of the Trident programme.

The Ministry of Defence audits the integrity of the UK's nuclear deterrent regularly for all threats and hazards and acts to ensure that it maintains the highest possible standards. The Strategic Defence and Security Review acknowledges the growing cyber threat and the importance of investing in cyber security across all of our capabilities. The Government has invested £860 million in new technology and capabilities since 2011 and will invest £1.9 billion over the next five years in protecting the UK from cyber attack and developing our sovereign capabilities in cyberspace. Our approach to protecting Defence capabilities against and mitigating the impact of cyber attacks spans technical, organisational, procedural and physical measures benefiting many different systems and networks, and investment is integrated across these measures. Submarines operate in isolation by design, and this contributes to their cyber resilience. I will not discuss further details for reasons of safeguarding national security.

The Ministry of Defence audits the integrity of the UK's nuclear deterrent regularly for all threats and hazards and acts to ensure that it maintains the highest possible standards. The Strategic Defence and Security Review acknowledges the growing cyber threat and the importance of investing in cyber security across all of our capabilities. The Government has invested £860 million in new technology and capabilities since 2011 and will invest £1.9 billion over the next five years in protecting the UK from cyber attack and developing our sovereign capabilities in cyberspace. Our approach to protecting Defence capabilities against and mitigating the impact of cyber attacks spans technical, organisational, procedural and physical measures benefiting many different systems and networks, and investment is integrated across these measures. Submarines operate in isolation by design, and this contributes to their cyber resilience. I will not discuss further details for reasons of safeguarding national security.

The Ministry of Defence no longer compiles national or regional defence industry employment statistics as they do not directly support policy-making or operations.

The 2014 Update to Parliament set out an estimate for the Successor submarine acquisition of around £25 billion, based on a four boat solution, spread over some 25 years. These estimates are currently being refreshed to inform the Comprehensive Spending Review and Strategic Defence and Security Review.

Once the new fleet of SSBNs come into service, we expect that the in-service costs of the UK’s nuclear deterrent, which include the costs of the Atomic Weapons Establishment, basing and disposals, will be similar to the current system, at around six per cent of the defence budget.

While we have no plans to replace the current Trident D5 missile, we are participating with our US partners in a programme to extend the current life to the 2060s. The estimated cost is around £250 million.

The 2014 Update to Parliament set out an estimate for the Successor submarine acquisition of around £25 billion, based on a four boat solution, spread over some 25 years. These estimates are currently being refreshed to inform the Comprehensive Spending Review and Strategic Defence and Security Review.

Once the new fleet of SSBNs come into service, we expect that the in-service costs of the UK’s nuclear deterrent, which include the costs of the Atomic Weapons Establishment, basing and disposals, will be similar to the current system, at around six per cent of the defence budget.

While we have no plans to replace the current Trident D5 missile, we are participating with our US partners in a programme to extend the current life to the 2060s. The estimated cost is around £250 million.

Ministry of Defence and Treasury officials are involved in scrutinising and assuring the costs and the levels of risk within the Successor submarine and Trident D5 missile life extension programmes, including before major investment decisions.

As stated in the UK Future Nuclear Deterrent 2014 Update to Parliament, the Ministry of Defence (MOD) is more than halfway through a five year, £3.3 billion, Assessment Phase for the Successor submarine programme.

To the end of financial year 2013-14, a total of £1,243 million has been spent on this Assessment Phase. The MOD expects to commit around a further £2 billion before a Main Gate investment decision in 2016.

Estimated spending for individual years is being withheld as it relates to the formulation of Government policy and release would prejudice commercial interests.

The expected £42 million reduction in cost results from changes to the way the Department pays for the Barrow facility improvements. The payment changes reflect a move from overhead recovery from BAE Systems to direct funding by the Ministry of Defence, and an associated reduction in the company's profit to reflect the reduced level of commercial risk.

Much of the plant and equipment within the new assembly shop will require upgrading and refurbishing from the existing stock to support the Successor submarine build programme. This includes presses, rotators and specialist welding equipment; the testing of this equipment will use steel from which test-pieces and prototypes will be manufactured.

The 2014 Update to Parliament explained that £261 million of funding has been re-profiled into the Assessment Phase. Of this, £206 million is to support Barrow infrastructure. The remaining £55 million is the £55 million referred to in the Long Lead Items section of the 2014 update.

As a recognised Nuclear Weapons State under the nuclear Non-Proliferation Treaty (NPT), the UK is not obliged to seek an independent authority to verify the reduction in the number of operational missiles and nuclear warheads.

Non-operational Trident missiles are stored in accordance with agreed procedures. The 2010 Strategic Defence and Security Review revision of the number of operational missiles did not change the UK entitlement to Trident missiles, which are supplied from a common pool in the US under a Government to Government arrangement.

Once processed, the fissile material from dismantled warheads is returned to the Ministry of Defence nuclear material stockpile.

As a recognised Nuclear Weapons State under the NPT, the UK is not obliged to place this material under international safeguards.

Further to my answer of 10 Sep 2014, (Official Report, column 618W), a number of reports were identified that relate to the impact of the detonation of a UK Trident warhead. This information is, however, being withheld to safeguard national security, because its release would prejudice the defence of the UK, and because it relates to the formulation of Government policy.

The total spent on studies to inform the decision on whether to refurbish or replace the existing warhead during the period until 30 September 2014 comprises £72.9 million on technology studies to support refurbishment of the current system and explore options for a potential future warhead; and £4.6 million on studies to support the decision whether to refurbish or replace the existing warhead.

The cost of retaining the nuclear deterrent at Faslane and Coulport cannot be separately identified from expenditure incurred for multiple activities at Her Majesty's Naval Base Clyde.

I refer the hon. Member to the answer I gave on 4 September 2013, Official Report, column 409W. The total net book value of the nuclear warhead stockpile is £273.7 million. There is no common net book value for individual warheads due to differing levels of depreciation.

The standard application of net book value takes account of depreciation which depends on individual assets' in-service dates.