Question to the Ministry of Defence:

To ask the Secretary of State for Defence, how many tests of UK Trident missiles have been carried out by each Vanguard class submarine (a) since 2010 and (b) in the last 20 years; and how many tests of US Trident missiles have been carried out in those same time periods.

Demonstration and Shakedown Operations (DASOs) are undertaken prior to the initial deployment of a ballistic missile submarine and also following long overhaul periods. To date there have been eleven UK DASO firings of the Trident II D5 missiles - all resulted in the submarine successfully being certified to return to the operational cycle.

Details of the date of the missile firing and the submarine involved are given below;

26 May 1994 - HMS Vanguard

19 June 1994 - HMS Vanguard

24 July 1995 - HMS Victorious

22 August 1995 - HMS Victorious

10 October 1997 - HMS Vigilant

10 October 1997 - HMS Vigilant

21 September 2000 - HMS Vengeance

10 October 2005 - HMS Vanguard

26 May 2009 - HMS Victorious

23 October 2012 - HMS Vigilant

20 June 2016 - HMS Vengeance

We do not hold records of US DASOs, but there have been over 160 successful test flights of Trident II D5 missiles since 1989.