Keir Starmer has said Britain’s nuclear deterrent is the front line of our defence as he warned the UK must not take its eyes off Russia amid the Iran crisis. The Mirror was given rare access to join the Prime Minister as he boarded a nuclear-armed Vanguard-Class submarine off the west coast of Scotland as it returned from a record 206-day deployment. His top-secret visit to greet Royal Navy submariners on "Day Zero" - their return to UK waters from their lengthy patrol - comes at a moment of sky-high global tensions. And his decision to showcase Britain's nuclear arsenal...