There has been coverage on radio, strandedatsea, and even interviews with top brass and sub captains and crew, actually doing drill for a missile launch.
Although there might be a deterrent to a national enemy, ie some regime decided (stupidly) to attack the UK, but if terrorists attacked, having nuclear weapons is ineffective. Indeed, a little before the election
Imagine the scenario - a bunch of terrorists decides to explode a dirty bomb carried in a light aircraft (or executive jet, who knows what they could buy) in central London. It would be far from impossible unless City Airport bans executive jets. Flight plan would be say Edinburgh to London in the morning arriving at 10:00.
If the pilot was part of the plot he could simply detour from the intended path to go right over Buckingham Palace and the bomb could be detonated at anything from 500 to 1500 feet above ground, ensuring wider coverage than some blast on the ground, making central London a wasteland for at least 30 years, stopping all forms of transport, wiping out banks, data centres, and a few million people killed or wounded or given radiation poisoning (whilst many specialists might also be killed - time the attack to coincide with some conference for cancer specialists, ie those who know how to best make use of radiation for good, and also know how to help someone through dangerous exposure.
If the pilot was not part of the plot, s/he could still be coerced or killed and the plane taken off course.
Now, there's been an explosion in London, 20% of the population in the area are incapacitated, the area is 'hot' so no one can move in to search of survivors, Parliament and various Government departments are devastated, and what would be your target for a retaliatory strike?