Thirty nations would be nuclear armed by now – that was the prediction in the 1960s.

In fact, it’s nine.

It’s the international agreement, with the International Atomic Energy Agency (IAEA), in 1953, and the Non-Proliferation Treaty (NPT) in 1970, which has made the difference.

The NPT authorised the five Permanent Members (P5) of the UN Security Council to maintain their nuclear weapons, but no other nation. You can argue whether this was ‘fair’, but it was a recognition of reality at the height of the Cold War.

The system has helped to keep the peace internationally. None of the other four nations who for certain have nuclear arsenals - Pakistan, India, Israel, and North Korea – are signed up to the NPT.

There has been much speculation, however, as to whether Iran is pursuing a nuclear weapons programme. It is a signatory to the NPT, and so is subject to inspections by the IAEA.

In 2007 an official ‘National Intelligence Estimate’ of the United States said that the US judged that Iran had abandoned its active nuclear weapons programme in 2003.

However, during the Presidency of Mr Ahmadinejad, Iran was found by the Security Council to have failed to meet obligations to come clean about its nuclear activities. Serious economic sanctions have been imposed in consequence.

Earlier this week, with Ben Wallace. Conservative MP for Preston North and the Wyre, co-chairman with me of the All-Party Parliamentary Group on Iran, and three other MPs, I spent two days in Vienna, where the IAEA is based, to find out more about the IAEA’s work on Iran.

We met its Director-General, Yukija Amano, and senior Ambassadors to the Agency.

There are intensive negotiations between the P5, Germany, and Iran to try to resolve these questions about Iran.

With attention on the Ukraine and Syria, Iran has been out of the headlines recently, but as the late-July deadline for these talks approaches it will come back into focus. Like my colleagues, I for one am now much better informed about the issues as a consequence of this visit.