Way back when, in the height (1960s) of the Cold War they used to test the 4-minute warning sirens that infested the UK back then. What you were supposed to do in those 4 minutes was never clear. Later, in Thatcher's regime, you were supposed to hide under a table.

All such things are very frightening. If you have ever heard a full wing of Vulcan nuclear bombers (my dad was a Vulcan captain) taking off when you didn't expect it (which you didn't, because of the Official Secrets Act) you will also know what dread is like.

I hope this isn't some bloody anti-Putin meaningless gesture by our ridiculous government, but I expect it is.

PS I am anti-Putin.