Gary McKinnon is not being extradited. How wonderful to be able to write these words which until the Home Secretary told me yesterday I did not fully believe could be true. Words do matter. When the prime minister said before the election that Gary McKinnon "is a vulnerable young man and I see no compassion in sending him thousands of miles away from his home and loved ones to face trial". We now know it really mattered. Compassion in words and now actions.

The deputy prime minister has said/sung sorry for breaking his pre election promise on tuition fees but I don't think any version of an apology would have been accepted if Gary had been extradited. His words that: "There is no excuse not to do the right thing and the only right thing to do is to prevent this vulnerable man being sent over to America" would have been repeatedly played back alongside photos of him standing on the picket line outside the Home Office with Gary's mum. But not now.

The promises given were to my constituent and they mattered to me as his MP. My constituent's interests came first and I would have resigned my government position as Owen Paterson's PPS if the government had not been true to its word. Since the decision my inbox has been full of messages from families and friends of people with autism or Asperger's syndrome. They take great comfort from the recognition and understanding of the serious impact of the condition. I have also received messages from those with mental health conditions who lack a voice. Words matter.

I said in the Commons yesterday that the Home Secretary had saved my constituent's life. Some MPs, such as the former Home Secretary Alan Johnson reacted with incredulity. It was of course Alan Johnson who in 2009 refused to step in and stop Gary's extradition when medical evidence made clear that he would take his own life. Back then in the House I accused him and his government of being "spineless". His reaction yesterday which sought to bring party politics in to the plight of a vulnerable suicidal man shows the search still goes on for his spine. Theresa May certainly found her spine yesterday.

I have the advantage of having seen all the medical evidence - both Gary's doctors and the Home Office's doctors. I also have the experience of 20 years as a criminal defence solicitor. Gary's medical defence was clear and compelling. He would take his life if extradited and no assurance could be given to authorities about preventing his death. Few people have been subject to so much scrutiny of their mental health by leading experts in the field of forensic psychiatry, autism and Aspergers' syndrome. No one in the UK has been effectively on bail for 10 years or, as far as Gary was concerned, on death's row. Those on both sides of the Atlantic who are quick to sneer at the medical grounds for refusing Gary's extradition should either take a long look at his medical reports or respect the Home Secretary's decision.

It hasn't taken long for some of the media to look for some bad news in the McKinnon story. The most ridiculous of which is George Galloway's rant that if Gary was a Muslim he would have been extradited. George should know better as a long standing supporter of Gary that his mental illness and Asperger's is blind to colour, race or creed. He should get off his sectarian bandwagon and applaud a right and just decision.

Yesterday in the Commons I sought another promise - that never again would a vulnerable UK citizen face 10 years of mental torture like Gary McKinnon and that the British sense of justice and fair play would return to extradition. This could be the legacy of Gary McKinnon. A life saved, promises delivered and legacy secured. Words matter.