What will happen is – UK’s missile defense, on every level, will go active. From long-range-SAM and AA-interceptor missiles to anything that can shoot, probably any hunter with a shotgun (you know, the famous stiff upper lip and so on). And you may be surprised what these things (not the shotguns, but anything else) can do these days.
If possible, the Prime Minister will order any UK Nuclear-Armed Subs still moored to get out of port at max speed, and dive for their lives, and order a full counter-launch from everyone else. Same for any and all surface ships.
There will not be any evacuation – not for close to 70 million people, who will not even have time to find rudimentary shelter, except maybe in the Tube and some other places. It will be impossible to evacuate over sixty million people in four minutes.
The thing about it is, for the last two decades, Russian military has been trumpeting their “high tech” weapons far and wide, and in Ukraine we have seen what they are really worth.
Western military industry, on the other hand, quietly kept improving their missile defenses (those same missile defenses, that Soviet Union couldn’t dream of matching in 1985, and why they eventually lost the cold war). About a decade ago, some US missile defense installation were deployed to Poland, and Russians were infuriated because they knew they had nothing to match them.
