If nuclear weapons remain in existence forever then sooner or later they _will_ be used again: either consciously by some govt, as at Hiroshima, or accidentally, or in response to a false alarm, or because they've fallen into the hands of a terrorist group
There was the incident in 1995, for instance, when a scientific research rocket launched from Norway looked on Russian radar like a nuclear missile: Yeltsin activated the "nuclear briefcase" & Russia was only minutes away from "retaliating"
And that was at a time when relations between Moscow & the NATO countries were the friendliest they've been in living memory
The _only_ way to make sure nuclear weapons won't be used is to dismantle them & not build any more
That applies to all nuclear weapons states but I think it applies in particular to Britain & France, bc if you look at the list (USA, Russia, China, France, Britain, India, Pakistan, Israel, N Korea) then those two manifestly have the weakest argument for needing a deterrent
If _Britain_ can only feel safe when it has nuclear missile submarines continuously patrolling the seas, then how on earth can you say Iran doesn't need the bomb? Or Venezuela? Ukraine? Saudi? Taiwan? Iraq? Just about any country, in fact?
But a world in which they all had it would not be a world in which nuclear war was less likely