Hornsey and Wood Green MP Lynne Featherstone has revealed she is writing a book about her successful campaign to legalise gay marriage.

The Liberal Democrat minister has written a number of draft chapters of a book telling the story of how she spearheaded a campaign to introduce same-sex marriage after entering David Cameron’s coalition government in 2010.

Ms Featherstone announced the plans during a special equal marriage talk at the Sherriff Centre in St James’ Church, Sherriff Road, West Hampstead, on Tuesday last week.

She was joined by the church’s vicar Fr Andrew Foreshew-Cain, who became the second gay priest in the country to marry under the new laws.

Ms Featherstone, who is yet to have secured a publishing deal for the book, said: “Whenever I go and make a speech anywhere there will be usually a young man who will come up to me and say, ‘Thank you, you’ve changed my life. You have changed everything.’ And then I cry and they cry.

“I think it’s a very profound piece of legislation. It was the step that said, ‘This is about equality.’”

During the talk, chaired by the Lib Dem Hampstead and Kilburn parliamentary candidate Maajid Nawaz, Ms Featherstone talked in depth about the journey that resulted in the passing of the Marriage (Same Sex Couples) Act 2013.

The former South Hampstead High School pupil said the impetus to push for the legislation came to her within days of becoming equalities minister in 2010 - during an “induction for newbie ministers” run by Labour’s Lord Andrew Adonis and former Tory deputy prime minister Lord Michael Heseltine.

“I don’t know if I would have known what to do if I hadn’t gone to this induction,” she said.

“Michael Heseltine’s advice was that as a new minister you will be hit by a tsunami of work and at the end of five years you’ll find you’re a good little minister and you didn’t actually do anything you set out in politics to do.

“So prioritise, choose something you want to do and be ruthless about it. It really took about three seconds to decide – it had to be same-sex marriage.”

In the wake of Lord Heseltine’s advice, Ms Featherstone said she drafted a proposal for same sex marriage which she sent to Home Secretary Theresa May, who was her secretary of state at the time as minister for women and equalities.

After receiving the backing of Ms May and subsequently the prime minister, she then unveiled the plans at the Lib Dem party conference in 2011.

Following consultation, the legislation was eventually passed by parliament in July 2013 and came into force on March 13 this year.

Ms Featherstone added: “This coalition has cost us dear in many ways. On one level it’s absolutely fantastic delivering Liberal Democrat policy but electorally it has its challenges.

“But I thought, ‘I’m going to do something liberal and I’m going to do something while I have the opportunity because I don’t know how many times in history that will happen.’”