Letters of Last Resort

I was watching PKA and Woody brought up the topic of Letters of Last Resort. For those of you out of the loop Letters of Last Resort are letters wriiten by the Prime minister of the UK that are given to the 4 awaiting Trident submarines stating which course of action to take in the case of his and his second in command's death: retaliate with nuclear weapons; not retaliate with nuclear weapons; use his own judgement; or place the submarine under allied country command. Which do you think would be the most appropriate choice and why? Personally, I would go with retaliate with nuclear weapons because if they launch nukes against my country and kill me and my second, then they deserve to be nuked back into the stone age.