“The doctors say, if there is a third time, that’ll be it. I will not survive this again,” says Vladimir Kara-Murza matter of factly. It’s six weeks since the second attempt on his life, via a highly sophisticated poison attack, ended in unlikely failure.

He is now back in his home of Washington, but already he is recuperating, planning his return to Russia to carry on his work as a leading figure in what he calls the ‘democratic opposition’ to the Putin regime – a course of action I describe as brave.

“I am not brave,” he says, “just stubborn.”

But that is not to suggest his wider responsibilities, not just to his homeland but to his wife and his three young children, have not crossed his mind.

“They almost lost their dad, twice,” he says, breaking almost into laughter. “It is fairly disconcerting to say the least when someone is trying to kill you every two years.”

Six weeks ago, Mr Kara-Murza, who is 35, found himself suddenly and totally incapacitated, as he had done in May 2015, but this time there was no shock and confusion, but a sense of familiar dread.

“What saved me is that I was with people,” he says, over the phone from Washington.

“The last time, two years ago, I was at a work meeting with colleagues. This time I was at my parents-in-law’s apartment. It happened so quickly, I couldn’t have called an ambulance. If I was alone, I would not be speaking now.”

So how does he explain what happened?

“I have no idea of the who, the when, and the how. When I am in Russia I have lots of meetings every day, in cafes, in restaurants. It could have been anyone.

“The only thing I am sure about is the why. I have no doubt that this was an attempt to kill rather than to scare. As doctors told my wife both times, the chances of survival was about five per cent both times. That is not how they scare you. That is how they kill you.

“I am confident that this is because of my political activities in Russia, in the democratic opposition to Putin’s regime.

“I don’t know if Putin would have ordered it, but there’s no doubt it is political. These were two attempts to kill me. The way it was done, it was a very sophisticated toxin, that shuts down your whole body in six hours.

"The way it was introduced was sophisticated, because I didn’t notice anything. And also, last time, my wife sent some samples out to a toxicology lab abroad, in France. They found traces of heavy metals, dozens of times over the normal limit, which proved that something abnormal was done, but they never found the exact toxin.

"It remains to be seen if we find something this time. This time, my wife and my lawyer got blood samples out to three toxicology labs in three different countries and they got it on day one.

“To be a highly sophisticated toxin that is not easily traceable, I think it must be people who either have been or who are currently connected to the Russian Special Services. There is no doubt about that.

“As for why? If you were to ask me what the most likely reason is, I would say it is my work on the Magnitsky law. My participation in the campaign, first of all, to get the Magnitsky Act passed in the US five years ago, that introduces sanctions on Russian human rights abusers, but with the help of many good friends we managed to do it.”

Mr Kara-Murza went to school in the UK, and to university too, where I happened to know him. He had boundless energy, and it was instantly apparent he was going places, not least because no matter what subject you were studying, he knew more about it than you.

On one occasion he produced a VHS tape recording of his dad, who has the same name, live on air on an independent Russian television channel, broadcasting as state authorities arrived to close the station down.

On another, he arrived at a lecture looking particularly ashen faced, having diligently reported to a newspaper – for whom he was moonlighting as London correspondent – some loose-lipped words at a talk from the then Nato Secretary General at the Cambridge Union. As a direct consequence, Belarus had threatened to suspend diplomatic relations with the bloc.

And another time, I happened to mention something I’d remembered from A-Level History, the Aventine Secession, when Mussolini’s opponents walked out of parliament in protest at the murder of Giacomo Matteotti, but succeeded only in enabling the dictatorship.

For the next three years, he mentioned it every time I saw him, a recollection that has since caused me some discomfort, given that two gruesome attempts on his life have not weakened his resolve.

“We always knew, for many years, that it is a risky vocation, being in opposition to Vladimir Putin’s regime,” he says, of his determination to continue.

“We know of many people who were driven to exile, put in prison, or are no longer with us in this world. These risks became much more tangible when Boris [Nemtsov] was killed.

"He was a close, personal friend. When he was killed that really drove it home. Now someone has tried to kill me twice, it makes you realise the risks. But I happen to think that what we do is important.”

What Mr Kara-Murza calls the "grotesque, byzantine" structure of the Putin regime makes the direct apportioning of blame for what has happened to him a complex thing, but for several years Mr Kara-Murza has been pushing his work on the Magnitsky Act all around the world.

It was signed into US law some years ago, and more recently into UK law.

The law, named after Sergei Magnitsky, a Russian lawyer who died in prison in Russia in 2009, is designed to prevent human rights abusers in Russia from keeping their wealth in Western countries.

It is Mr Kara-Murza’s view that since more powerful names have been added to the sanctions list in the last few years, the risks posed by his activities have become more severe.

Mr Nemtsov, godfather to Mr Kara-Murza's youngest daughter, was assassinated on a bridge by the Kremlin two years ago.

“They killed Boris Nemtsov because he was the strongest opposition leader. He was unique. Two years have passed and no one has replaced him,” Mr Kara-Murza says.

“There is a Russian saying that no one is irreplaceable. Well that’s not true. He was irreplaceable, and they knew it. Those who killed him, knew it. That’s why they killed him.

“But me? I help organise rallies and go round the country but they’re not really afraid of that, the regime. What they are afraid of is getting on that sanctions list.

"The nature of this regime is similar to what we had in Soviet times. We have media censorship, the lack of free and fair elections, we have political prisoners, dozens of them, so it is similar, but in one very important way it is different. And that is that although members of the Soviet politburo were putting dissidents in jail and engaging in anti-Western propaganda, they did not keep their money in Western banks.

"They did not send their kids to study in British schools. They didn’t buy real estate and yachts and luxury cars in western countries. These guys do. They want to rule inside Russia, like it’s a Third World dictatorship, but they want to use the opportunities of Western democracies for themselves. We think that hypocrisy and that double standard has to stop.”

In the coming weeks, if not days, Foreign Secretary Boris Johnson will be heading to Moscow to meet the Russian Foreign Minister, Sergei Lavrov, a meeting that the British Government has been keen to stress should not be seen as an attempt to rebuild or improve relations.

That Donald Trump appears so unwilling to criticise Vladimir Putin is, for many, evidence of deeply sinister goings on below the surface, but Mr Kara-Murza sees things differently.

“We have seen this all before,” he says. “Remember the Obama administration? They wanted a ‘reset’ with the Russian regime, remember. Hillary Clinton pressed that reset button. George W Bush said he had ‘looked into Vladimir Putin’s eyes and saw his soul’.

"The Trump administration is just doing the same thing. But in the end, one is a a democratic system under the rule of law, and in the end there cannot be a convergence of interests between a modern democratic system and a corrupt, authoritarian dictatorship. There can be short term deals, tactical deals, which I think are a very bad idea, but we’ve seen it before, and we saw how it ended every other time.”

In the meantime, a perception of Western impotence has allowed Mr Putin to dictate terms in Syria in brutal fashion, and the Europe Union’s eastern neighbour, Ukraine, has been a victim of Russian aggression, leaving many in the West wondering whether they should be doing more to deliver change in Russia.

But Mr Kara-Murza believes such thoughts are misguided.

“We always get asked, well meaning people ask us, what can we do? They say, people like Boris Johnson, like Rex Tillerson, how can Western leaders help the Russian democracy movement, and I always answer in the same way.

"We are not asking for your help. It is our task. It is our job to change Russia. To bring the rule of law and democracy back to Russia, and we will do it. The only thing we are asking Western leaders, Western Foreign ministers, is to stop helping Mr Putin, first of all by treating him as a respectable partner on the world stage, and secondly, most importantly, by not allowing his cronies to use Western countries, including the UK, perhaps primarily the UK as havens for the wealth they have looted from the Russian people. This is all we ask. The rest we will do ourselves."

And these are particularly pointed words, with the World Cup in Russia only 15 months away, and various calls to boycott beginning to crescendo.

“It’s a difficult one,” Mr Kara-Murza admits. “Sportspeople should be participating. It is what they do. But I would certainly say that the leaders of Western countries should not take part in the opening ceremonies, because that does legitimise Putin.

"Having Vladimir Putin flanked by Theresa May, Angela Merkel, whoever the French President is, that does legitimise. At the Sochi Olympics, Boris Nemtsov’s position was that sportsmen should go and compete but political leaders from democratic countries should not go. I think that should still be the case now.”

His own degree, by the way, was in history, and though Russia’s is unrivalled in its unpredictability, it is also a source of optimism.

“Nothing lasts forever,” he says. “Putin cannot last forever. Everywhere I go, we hold rallies, debates, public meetings, people, especially young people, who reject this regime and everything it stands for. They reject its egregious corruption, its autocracy and authoritarianism, they reject what it stands for in terms of its relations with the outside world, its aggression, and they want to see Russia become a normal, democratic European country.

"There are many people like that. This is what gives us hope. These people represent the best hope for Russia’s future. The end game is pretty clear. A day comes, eventually, however much the propaganda machine works, however much they rig elections, kill opponents, the day always come when the active part of society says enough is enough.”

Maybe it will happen, maybe it won’t. But one thing is clear, extraordinary things will have to have happened if Vladimir Kara-Murza is not standing there if it does.