I’ll approach the hot topic of a ban on Russian oil by way of personal anecdote: I’ve never been a soldier or a spook but I have twice found myself ensconced in secure Nato conference rooms. The first occasion was a group visit to the military alliance’s Brussels headquarters 42 years ago, when an unsmiling American defence expert introduced us to the concept of ‘Mutually Assured Destruction’ – whose acronym was the key to the tense but relatively stable Cold War stand-off.