The most upbeat and positive image I've seen lately was not the sort of thing that usually warms the heart, or makes you think that the world has become a better and safer place.

A line of middle-aged and elderly men in (rather ill-fitting) suits, smirking but still looking stiff and uneasy as they stood in a bland anteroom in an upmarket chain hotel in Geneva. Among them was one woman, and she is maybe the unlikely heroine of this week, or even this year.

This was Baroness Ashton, the EU's foreign policy supremo, and someone who has been regularly mocked for having very little to do, and not doing it very well either. Yet she was the key player in the line- up.

The gents in suits were the foreign ministers of China, Russia, France, Iran and the UK - plus Secretary of State John Kerry of the US. They had just completed a breakthrough negotiation that should result in Iran curbing its nuclear programme, and stop it building a nuclear bomb. And it was Catherine Ashton who, according to John Kerry, showed the persistence and doggedness needed to keep the talks going. She also acted as an acceptable and respected go-between with the Iranians.

So Catherine Ashton had come in from the cold, and over five gruelling days helped to broker what appears to be, if not a global diplomatic triumph, at least a deal that represents positive progress.

Of course, our planet being what it is, not everyone is happy. Prime Minister Netanyahu of Israel was predictably dismissive, announcing that far from being a safer place, the world was now much more dangerous. More ominously, if equally predictably, right-wing politicians in Washington were scathing about the deal and threatened to wreck it. The hard-line Republican Marco Rubio immediately and perversely called for increased sanctions against Iran.

The trouble in Washington is that President Obama is grievously weak. He is faced with an insular, truculent claque of Republicans who resent him and are all too happy to wreck most of what he is trying to achieve. But he can't deal with them. He doesn't want to get his hands dirty with the kind of grubby but effective power- broking that the likes of Lyndon Johnson worked so hard at.

Elsewhere, as the Geneva deal was picked over, it was indeed clear that some of the ramifications were mixed. If Israel is now more than ever isolated, President Assad of Syria is strengthened. Repellent as he and his regime are, this may be no bad thing in terms of global security.

The greatest current threat to world peace may well be the rapidly growing tension between Sunni and Shia Islamists. Saudi Arabia and most of the Gulf states are on the Sunni side, if that is the right phrase, and have close links with al Qaeda. The Geneva deal is very bad news for them. In that sense, it might be misguided to be too sanguine.

Meanwhile, President Putin of Russia now possesses more diplomatic clout than anyone else around. His foreign minister, Sergei Lavrov, apparently said little at Geneva but still made some key interventions.

He and Mr Putin are still basking in the afterglow of their earlier success when they managed to prevent Syria being attacked by global powers, and in the process showed up President Obama as a man who had seriously miscalculated world opinion.

Not so long ago Russia's diplomacy was an international joke. Its embassies were being closed and its diplomats were being sacked. Now under Mr Lavrov, who held the key post of Russian Ambassador to the UN for several years, there is a renaissance of Russian soft power. In some parts of the world - Eurasia especially - Russia is rapidly regaining influence.

The last G20 summit, at St Petersburg two months ago, was a triumph for Mr Putin and a humiliation for Mr Obama. Yet the US has three long years to wait for a new, tougher and more effective president.