Thanks for the recommendation, I've just finished watching it. Very interesting! I do enjoy a bit of war-gaming.
Now I see why my question didn't make a whole lot of sense. I was trying to drive at 'if we didn't have Trident, we wouldn't be a target' but we were a target for our conventional military actions, so my point was moot.
I see your point - the Russians seemed very contrite, so maybe they wouldn't have fired the ICBM's if the Americans hadn't hit back, and then Trident would have worked as a deterrent (sort of, although not really, because basically an entire land war was already in progress before it got to that stage).
I don't know if it changed my mind. The revelation that most wouldn't authorise a retaliatory attack on population centres rather removed Trident's 'second strike' capability as a reason for supporting it, and the film rather adequately demonstrated that Britain's nuclear status, combined with its very small amount of firepower and total lack of influence on Washington, makes us a target but without much corresponding influence.
The other, rather more urgent feeling I had watching it was just how dumb it was for George W Bush to push for admitting Ukraine and Georgia into NATO, and how imperative it is that we stop any further NATO expansion, forever.
Good programme though!