There is nothing more important to the Prime Minister of the United Kingdom this week than his nuclear weapons. And there is nothing less important to him than the men who provided them. As Keir Starmer leads a last-ditch bid by European nations to win US support back for Ukraine, he is relying on the fact he has at least one Vanguard-class submarine armed with 64 nuclear-armed missiles patrolling the seas. It is that guardian, alone, which keeps Vladimir Putin at arm's length on the other side