I agree that is the legal case - they are part of the UK and there would be a lot of reaction - but to use N weapons? I don't think so........
I don't think may people would see it as "a major challenge to our very existence as a nation". Now if the pesky Russians suddenly took a block booking on Eurostar and cross-channel ferry's ... maybe
You're not going to take the risk of killing 65 million people and turning the UK into a charred cinder over 1500 or so deaths I'm afraid - there'd be a lot of posturing and maybe a lot of cruise missiles fired off but, as ever, the poor bloody soldiers, sailors and airmen are likely to be sacrificed. It's the same the whole world over
You're right about First Use - from Wiki:-
In March 2002,
British defence secretary Geoff Hoon stated that the UK was prepared to use nuclear weapons against "
rogue states" such as Iraq if they ever used "weapons of mass destruction" against British troops in the field.
[28] This policy was restated in February 2003.
[29] In April 2017 Defence Secretary
Michael Fallon confirmed that the UK would use nuclear weapons in a "
pre-emptive initial strike" in "the most extreme circumstances".
[30] Fallon stated in a parliamentary answer that the UK has neither a 'first use' or 'no first use' in its nuclear weapon policy so that its adversaries would not know when the UK would launch nuclear strikes.
[3