The book is based on extensive correspondence between the two, even though Devi did not know English. She dictated her replies to Moxham's letters and the two became friends.
Titled India's Bandit Queen and Me, the book, writer Moxham says, "above all, this is the story of a friendship".
Narrating the course of events that led to his friendship with one of the most feared dacoits at one time, Moxham says: "In 1992 I did a very strange thing. I wrote to Phoolan Devi, who was languishing in an Indian jail. She had surrendered under a deal that should have led to her release the previous year"
He adds: "Although illiterate, she dictated a reply and we corresponded regularly. I gave her some help and advice. Phoolan was finally released in 1994. I met with her in India that year and we became friends. On my many visits to India in the following years I stayed and travelled with her."
Moxham, a former book conservator and lecturer, spends most of his time living in London and travelling in India. He is the author of Tea - Addiction Exploitation and Empire (2003) and The Great Hedge of India (2001).
"She was an amazingly cheerful woman, given all the trauma she had experienced in her life. She was always smiling and cracking jokes even though she had a harsh and poverty-stricken childhood and was victim of what I believe was a serious miscarriage of justice - for which she spent nine years in jail", BBC quoted Moxham as saying while recalling his association with her.
On her portrayal in director Shekhar Kapur's film Bandit Queen, he said: "That film showed her as being involved in the killings even though she always denied it and was not even convicted when it came out."
In fact Phoolan Devi had a real heart for the poor. When she was in prison she arranged for her food to be smuggled out so that it could be given to members of her family who lived in acute poverty, he added.
After her release from prison and entry into the Lok Sabha, he said Devi had none of the trappings of power shown by other politicians.
"I remember her on her knees cleaning her flat because she refused to employ servants. She was also extremely charismatic - the sort of person who could walk into a room and instantly command attention", Moxham said.