How well has that worked in the past?

Well I suspect this is some trap you are setting, but, with the exception of the Falkland Islands conflict, I can't remember any NATO COUNTRIES BEING ATTACKED, why don't you enlighten me, when has the NATO Alliance been required and failed to step up to the mark? Iraq? No we invaded, Afghanistan, no we attacked AQ, to deny them a base there, Balkans? No peacekeeping then SFOR, Sierra L, no, no no😃. Perhaps you think NI? No nuclear D required there...

Perhaps Korea? No UNITED NATIONS......

Eh! How would Russia invade without first going through Europe, do you think they would sail up the Thames like William of Orange? Or do you think it will be via hull port, enough Russian fishing ships dock there, no pun intended, but that is no catch.

I've got a magic rock that protects me from tigers. Since I've never been attacked by a tiger, it clearly works.

America is only going to launch nukes to defend London if American politicians believe there's something to be gained worth losing American cities in return. Personally, I can't see anything that would possibly be worth that to them.

Well, where were they during the Falklands conflict?

I believe you are forgetting Monica's missiles during the Balkan conflict.

If you wish to rely completely upon others that's fine. But it seems to be a little chicken shit to me.

The Royal Navy barely has enough ships for a decent Regatta these days, and nowhere near enough to fight off the Russians. And the government scrapped the last marine patrol aircraft a while back, so they'd probably still be drinking G&Ts when the Russian fleet docked in London.

You do understand the range of ICBMs, don't you?

To be fair, I don't believe Thatcher invoked the NATO treaty at that time. But no-one in their right mind expected the Germans or Turks to help recapture a couple of islands they'd never heard of, if she had.

Edit: it's probably worth noting that, at the time, the MoD was rolling back their independent capabilities in favour of only retaining those which were required as part of NATO (e.g. for anti-submarine work in the North Atlantic). Had the Argentinian government not been run by idiots, they could have waited a year and Britain wouldn't have had anything capable of taking the islands back without NATO support.

It's probably also worth noting that seeing nuclear-capable bombers dropping bombs on the Falklands must have caused a few brown trouser moments in Buenos Aires. A couple of nukes dropped on Argentina could have eliminated most of the military opposition.

ICBM do not invade, they destroy. I do have an inkling of their range yes, if you need to know, look it up on google...

What real threat is prevented by the possession of Trident ? Next time there is an attack on the Tube in London, will the MinofDef nuke ISIS ?

Not even one hypothetical scenario where Britain would want to use sub-based nukes. Not one. Just rationalisations that the French have 'em and that we can't rely on the yanks. Oh, and it's relatively affordable so why not.

Affordable, ha ha, since when as any big defence contract come in on budget, that figure you mention with inflation, cost overruns and project extension is likely to be close to 1 trillion. Milliband and Cameron both want it, so they can both lie about the cost and neither will correct the other. I say get rid. Unlimited wants, limited resources. If you want NHS, better education, a MOD that has weapons it will be able to use in a conflict, dump trident.

My 'affordable comment' was ironic, so I hope that wasn't aimed at me. I agree with your last sentence.

I think you and me are reading the same book, same page, same line .....

Spend a fortune on something you pray will never be used, if you do use it, chances are everyone including the yanks are using it too, pointless waste of UK taxpayers money.