The arguments for or against nuclear deterrence aren't really the point here;it's the fact of Mr Corbyn's intention to use the UK Defence budget as a Labour Party slush-fund to pay an electoral bribe to would-be supporters in the defence industry.
The Corbyn plan would swallow a gigantic sum of our money-and contribute no more to the nations defence than if he'd paid Red Robbo and his comrades to build two million Austin Allegro's and dump them in the North Atlantic!