RHU, SCOTLAND - JANUARY 20: WOZ Johnston in the weapons room on HMS Vigilant, submarine on January 20, 2016 in Rhu, Scotland. HMS Vigilant is one of the UK's fleet of four Vanguard class nuclear-powered ballistic missile submarines carrying the Trident nuclear missile system. A decision on when to hold a key Westminster vote on renewing Trident submarine class is yet to be decided senior Whitehall sources have admitted. (Photo by Jeff J Mitchell/Getty Images)
