I have a recollection of cabinet papers being published in book form aound 15 or more years ago which outlined the underlying argument (or logic) of Chevaline and the issue of Moscow.
As a dilemma it represents a fascinating study in terms of spending a huge amount of money, reducing the number warheads delivered, with the intent of leveraging the delivery of those that remain to their intended target.
At the same one might it shows that how just having an allegedly functional ABM system can benefit you by causing your adversary to spend a lot of money to reduce the number of warheads they can throw back at you. In effect the Moscow ABM defence knocked out a third of UK missiles before they ever went to sea on patrol.