Moving forward, we need to recognise the important role our nuclear deterrent plays internationally. Despite the global security environment having changed markedly since 1940, to abandon our deterrent now would only serve to undermine our own security, the security of our allies and that of liberal democracy globally.
Why not attend? The government explanation for non-attendance - once you get beyond complaints that the conference goals are 'unclear' - is that the conference may talk about the possibility of a negotiated global ban on nuclear weapons. Our government doesn't believe that such a ban is negotiable. So herein lies the contradiction.
What we need to do now is go further... to imagine, and then create, a world without war. With the hideous death-toll in Gaza, the chaos in Syria and Ukraine, the turmoil in Libya, that might seem a long way from the reality of 2014. But the important first step is to say "this is possible", and then to start to plan the actions needed to bring a peaceful world into being.
Why are we planning on spending £100 billion to renew a weapon system floating around in submarines off the coast of Scotland when it could completely destroy us and our climate, leaving radiation for years to come? If Britain chooses to renew Trident in 2016, this is ultimately the choice we will make.
A layer of our political elite still thinks that Britain's power and status can be secured by Cold War weapons. But others already understand that the challenges lie in climate change, hunger, injustice - and the asymmetrical warfare in varying forms that those problems will increasingly bring if unresolved. This is where the thinking of our political class needs to be.
Nuclear apocalypse has been avoided. Iran has agreed to curb its nuclear activity. That's what they tell us anyway. Let's not get ahead of ourselves; even if Iran's cooperation is genuine, world leaders and their Iranian counterparts are not about to hold hands, hug it out or start tweeting funny cat memes to each other.