Question to the Ministry of Defence:

To ask the Secretary of State for Defence, how long the vanguard-class submarines have been on patrol at sea on average in each of the last 10 years.

The Royal Navy has successfully maintained Operation RELENTLESS, the Continuous At Sea Deterrent, for an unbroken 55 years. We do not disclose details of the Operation, including the duration of time spent at sea, as such information could be used to undermine the security and capability of the mission and our personnel.