3.5 The Strategic Defence and Security Review supported the political, military and industrial need for seven submarines. The Review also slowed the Astute Class build programme to reduce short-term costs and to compensate for a four-year delay to the in-service date of the follow-on Successor nuclear deterrent submarine programme to avoid a production gap in the submarine construction industry. The need to align with the Successor submarine production stretched out the seven-boat Astute build programme by a further 96 months in 2010-11. This resulted in an average delay of 28 months to each of the Astute Class submarines over the past three years. Figure 15 overleaf indicates that, under current plans, it will take over ten years to complete each of the latter boats. For example, work is due to start on boat seven in early 2014 and the vessel is not currently planned to be ready to deploy until mid-2024.
3.6 Building seven Astute boats and slowing the build programme risks having insufficient submarines to undertake the number of tasks envisaged by defence plans. Since 2004 there have been periods when the Department has not had enough submarines ready to meet the classified availability requirement. As noted in this year's Astute project summary sheet the Department is currently reporting that the feet will not meet the availability requirement for submarines over part of the next decade. If the classified availability requirement is to be met with fewer submarines, then the Department will need greater availability of the new Astute Class than has been the case with the previous feet.