Gordon Brown’s declaration on Wednesday night that he backs the continuation of the Trident-based nuclear deterrent is politically highly resonant.

It is the most striking example the chancellor has given of his determination to face down the left of his party: MPs and activists who wrongly see him as someone who will end the modernising New Labour course charted by Tony Blair. Many of these MPs have viewed the decision on whether to maintain Trident as totemic for Labour. Some will be angered by Mr Brown’s strong indication that the military will get what it wants.