You are also arguing from the point that the first strike would be launched solely from missile silos inside Russia, while the task force might just as well be destroyed by nuclear torpedoes or AShM fired from hunter submarines shadowing the surface vessels, or from strike aircraft.
The only way to avoid a nuclear strike is by not being targeted by it. Peak oil is not an energy crisis. It is a liquid fuel crisis.
I was only arguing on the basis of missiles launched from silos on the basis of flight speeds you were quoting
The only way to avoid a nuclear strike may be to not be targetted by it, but Strategic Missiles have a horendously high failure rate, you'd need to be certain that you would kill every possible retaliating ship. This lack of certainty is where deterrence lies. Any idiot can face a crisis - it's day to day living that wears you out.
Unless you have subs. Peak oil is not an energy crisis. It is a liquid fuel crisis.
I remember some information on the topic during the north corea crisis: they have missiles, they have nuclear bombs, but they don't have (seemingly) nuclear bombs on missile. A free fox in a free henhouse!
So you take out the UK's entire deterrent and a few cities. Taking out London and maybe Birmingham and Manchester would be enough to put the UK back a century, because so many business and government records, communication systems and infrastructure management systems are based there.
Food deliveries would stop almost instantly, emergency rations would last a few months at the outside, and the UK would be dead as a country. Even without bombing the other cities, you'd lose anything up to 75% of the population over the next year or so.
So - then what? Even if there's enough of a government left to surrender formally, are you going to march in an occupy what's left, and create a new government? Why would anyone bother?
The Soviets had ideological momentum, so it wasn't completely impossible to imagine them wanting to invade Europe and the UK.
Modern Russia, not so much, except as an act of machismo and political spite. Likewise for China.
Iran, India, Pakistan, and NK might all want to try, but they wouldn't have the resources to launch a decapitation first strike - they'd go straight for the cities.
So really if Trident has a purpose at all, it's as a revenge weapon, guaranteeing retaliation against these second and third rate players. And they'd be just as vulnerable to a cruise-launched bomb run as they would be to an SLBM, so the submarine-launched angle starts to look slightly unconvincing.
