The story of Alexander Litvinenko often seems like it came from the pages of a spy novel rather than real life.

An ex-spy escaping to England, poisoned with radioactive polonium via green tea in a swish London hotel, a killing traced to the top of the Russian government.

Yet to hear his widow, Marina Litvinenko, talk about what happened is to be reminded that in fact this is an all too real story of a husband and father to a young son who was murdered by people in power and for whom justice seems unlikely.

"He was just a great man," she told an audience in Brighton. “He tried to save us, his family. He believed England would be a safe, nice place to live."

She shared the stage at the Sallis Benney theatre with the Guardian's former Moscow correspondent Luke Harding who reminded us of Litvinenko's deathbed assessment that while "the whole world will see my case as political - my case is not political; my case is criminal."

Mrs Litvinenko says she hopes one day to see people punished for her husband’s killing, and the same to happen for all the other, less high-profile people who have met a similar fate in Putin’s state.

"I never fight against; I fight for," she said. From the level of interest at this event, it seems likely the pressure for that will only grow.