Question to the Ministry of Defence:

To ask the Secretary of State for Defence, what refits of Royal Navy submarines there have been by (a) name, (b) year, (c) length of refit, (d) time taken to complete the refit, (e) the contractor undertaking the refit and (f) the cost of the refit in the last ten years.

There have been two submarine Deep Maintenance Periods (refits) during the last ten years. HMS Vengeance underwent a refit from March 2012 to February 2016 at a cost of £322 million. HMS Vanguard’s refit and refuel commenced in February 2016. Whilst HMS Vanguard has left His Majesty's Naval Base (HMNB) Devonport, the upkeep project continues with post refit sea trials. I am withholding the estimated cost as its disclosure would prejudice commercial interests.