In an old townhouse in East Boston an elderly stooped man is tending rare orchids in his shabby office. His Labrador Sally lies on the floor between stacks of academic papers watching him as he shuffles past.
This is Dr Gene Sharp the man now credited with the strategy behind the toppling of the Egyptian government.
Gene Sharp is the world's foremost expert on non-violent revolution. His work has been translated into more than 30 languages, his books slipped across borders and hidden from secret policemen all over the world.
As Slobodan Milosevic in Serbia and Viktor Yanukovych in Ukraine fell to the colour revolutions which swept across Eastern Europe, each of the democratic movements paid tribute to Sharp's contribution, yet he remained largely unknown to the public.
Despite these successes and a Nobel Peace Prize nomination in 2009 he has faced almost constant financial hardship and wild accusations of being a CIA front organisation. The Albert Einstein Institution based on the ground floor of his home is kept running by sheer force of personality and his fiercely loyal Executive Director, Jamila Raqib.
In 2009 I began filming a documentary following the impact of Sharp's work from his tranquil rooftop orchid house, across four continents and eventually to Tahrir square where I slept alongside protesters who read his work by torchlight in the shadow of tanks.
Gene Sharp is no Che Guevara but he may have had more influence than any other political theorist of his generation.
His central message is that the power of dictatorships comes from the willing obedience of the people they govern - and that if the people can develop techniques of withholding their consent, a regime will crumble.
For decades now, people living under authoritarian regimes have made a pilgrimage to Gene Sharp for advice. His writing has helped millions of people around the world achieve their freedom without violence. "As soon as you choose to fight with violence you're choosing to fight against your opponents best weapons and you have to be smarter than that," he insists.
"People might be a little surprised when they come here, I don't tell them what to do. They've got to learn how this non-violent struggle works so they can do it for themselves."
To do this Sharp provides in his books a list of 198 "non-violent weapons", ranging from the use of colours and symbols to mock funerals and boycotts.
Designed to be the direct equivalent of military weapons, they are techniques collated from a forensic study of defiance to tyranny throughout history.
"These non-violent weapons are very important because they give people an alternative," he says. "If people don't have these, if they can't see that they are very powerful, they will go back to violence and war every time."
After the Green uprising in Iran in 2009 many of the protesters were accused at their trials of using more than 100 of Sharp's 198 methods.
His most translated and distributed work, From Dictatorship to Democracy was written for the Burmese democratic movement in 1993, after the imprisonment of Aung San Suu Kyi.
Because he had no specialist knowledge of the country he wrote a guide to toppling a dictatorship which was entirely generic. But Sharp's weakness became the strength of the book allowing it to be easily translated and applicable in any country of the world across cultural and religious boundaries.
The book caught fire figuratively and literally.
From Burma word of mouth spread through Thailand to Indonesia where it was used against the military dictatorship there. Its success in helping to bring down Milosevic in Serbia in 2000 propelled it into use across Eastern Europe, South America and the Middle East.
When it reached Russia the intelligence services raided the print shop and the shops selling it mysteriously burned to the ground.
The Iranians became so worried they broadcast an animated propaganda film on state TV - of Gene Sharp plotting the overthrow of Iran from The White House.
President Hugo Chavez used his weekly television address to warn the country that Sharp was a threat to the national security of Venezuela.
After recent allegations of vote rigging in her home country of Gabon, supermodel and activist Gloria Mika travelled to Boston to meet Sharp.
"I felt like I was going to meet the main man in terms of non-violent resistance in the world," she says. "It was important because some of the Gabonese were talking about a violent option. They were saying, let's go and kill some people and I was able to say: 'Hang on guys there's another option here.'"
The Serbs who had used his books as a theoretical base for their activities founded their own organisation called the Centre for Applied Non Violence (CANVAS), and alongside their own materials have carried out workshops using Sharp's work in dozens of other countries.
When I met Srdja Popovic the director of CANVAS in Belgrade in November he confirmed that they had been working with Egyptians. "That's the power of Sharp's work and this non-violent struggle," he says. "It doesn't matter who you are - black, white, Muslim, Christian, gay, straight or oppressed minority - it's useable. If they study it, anybody can do this."
Photocopies in Arabic
By the time I arrived in Tahrir square on 2 February many of those trained in Sharp's work were in detention. Others were under close observation by the intelligence services and journalists who visited them were detained for hours by the secret police. My own camera equipment was seized as soon as I landed.
When I finally reached one of the organisers he refused to talk about Sharp on camera. He feared that wider knowledge of a US influence would destabilise the movement but confirmed that the work had been widely distributed in Arabic.
"One of the main points which we used was Sharp's idea of identifying a regime's pillars of support," he said. "If we could build a relationship with the army, Mubarak's biggest pillar of support, to get them on our side, then we knew he would quickly be finished."
That night as I settled down to sleep in a corner of Tahrir square some of the protesters came to show me text messages they said were from the army telling them that they wouldn't shoot. "We know them and we know they are on our side now," they said.
One of the protesters, Mahmoud, had been given photocopies of a handout containing the list of 198 methods but he was unaware of their origins. He proudly described how many of them had been used in Egypt but he had never heard of Gene Sharp.
When I pointed out that these non-violent weapons were the writings of an American academic he protested strongly. "This is an Egyptian revolution", he said. "We are not being told what to do by the Americans."
And of course that is exactly what Sharp would want.
Ruaridh Arrow's film, Gene Sharp: How to Start a Revolution, will be released in spring 2011