Letter from senior figure in local party suggests MP's decision to come out in 2010 was 'final straw' for some party members

A gay former minister has fought off a campaign in his affluent Surrey constituency by opponents, who highlighted his sexuality, to block him standing as the Conservative party's candidate at the next general election.

Crispin Blunt, who served as prisons minister between 2010 and 2012, won a postal ballot of the membership of Reigate Conservative constituency association after senior national party figures rallied to his side amid fears that a defeat would harm the modernisation of the party.

Blunt hailed his "thumping" victory in the ballot of about 400 members – by a margin of five to one – and called on opponents who forced the vote to consider their positions on the association's executive council.

"I was astonished by the irrational and unexpected action of the executive council in September," the former army officer said as he suggested they should ask how best they can unite the party.

Blunt won by a five to one margin in the postal ballot. A Tory source said: "We are very pleased. Crispin Blunt is a great champion for local issues."

Downing Street was hugely relieved by the margin of Blunt's victory, which allowed the party to depict opponents, some of whom had highlighted his sexuality, as marginal figures. One senior member of the Reigate association had described Blunt's "totally unnecessary announcement that he was 'gay'" as the final straw.

Modernisers feared that a defeat for Blunt, 53, so soon after David Cameron's showdown with traditionalists over gay marriage, would prompt critics to say that the Tory grassroots is out of touch with modern Britain. Supporters of Blunt dubbed their campaign to save the former minister "Operation Meteor" – a reference to the meteorite that killed the dinosaurs – in the wake of evidence of homophobia after he came out in 2010, ending his marriage to his wife, Victoria.

Supporters of Blunt had dubbed their campaign to save the former minister "Operation Meteor" – named after the meteorite that killed the dinosaurs – in the wake of evidence of homophobia after he came out in 2010, ending his marriage to his wife Victoria.

One senior member of the association described Blunt's "totally unnecessary announcement that he was 'gay'" as the final straw.

Opponents of Blunt, who forced the postal ballot after securing a majority on the association's executive council to block his automatic re-selection as the party's candidate, insisted they wanted to unseat him because they claimed that he neglected his duties as a constituency MP while serving as a minister.

But a letter from a senior figure in the local party to a Blunt supporter showed that his decision to come out in 2010 was a major factor. Roger Newstead, the chairman of the Reigate South and Earlswood Branch, set out the thinking of the traditionalists after a Blunt supporter protested at the decision to force a postal ballot.

In the letter, Newstead told Dr Ben Mearns, who resigned from the branch commitee: "I do not know what motivated my executive colleagues but I suspect that Crispin has been the author of his own misfortune. There is no doubt in my mind that his very public and totally unnecessary announcement that he was 'gay' was the final straw for some members, particularly those in the north of the borough, with whom there had been a number of previous disagreements on policy matters.

"A number of lady members were very offended by the manner in which his marriage broke down. Apparently Victoria's version was very different from Crispin's."

Newstead defended his letter to Mearns, which was prompted by allegations that the executive council, which forced the postal ballot, had acted in a homophobic manner. "It was a private letter to a member who had expressed some strong views to the branch committee meeting which included the observation that the executive were homophobic. Being a member of the executive I resented that and I put forward a selection of other reasons as to why some people felt the way they did.

"I still say it was unnecessary [for Crispin Blunt to come out]. To me it was an error of judgment. I wouldn't have done anything like that. I would have just said if anyone had asked me: politicians have a unique lifestyle, it doesn't suit everybody and there is a long history of parliamentary marriages breaking down. You don't have to go out and tell people you have got homosexual tendencies – that sort of thing you know. It is a private matter and it shouldn't have been put in the public domain. He put it in the public domain."

The suggestion that Blunt's former wife was at odds with the MP ran into trouble when she made a show of support for her former husband at the association's annual dinner earlier this month addressed by Eric Pickles.

Blunt was allowed to make a brief speech at the dinner but was banned from mentioning the vote on the grounds that such remarks would be against the rules.

Tony Collinson, a former chairman of the association, said on Monday that he disapproved of homosexuality, saying: "I'm a Christian and I don't think in fact that it is right. But that is entirely up to people. They must search their own consciences."

Collinson declined to say how he had voted. "I'm not prepared to tell you what my view is. Everyone is entitled to their own view and we had a secret ballot on it and I don't think I should make any comment.

"What I said was if what we know now had been known at the time of his selection in 1997 it is quite possible that he would not have been selected. I can tell you that the selection committee was not happy to have anyone that might have had any sort of thing in the cupboard."

Collinson said in 2002, in the wake of the decision of Alan Duncan to come out, that he would not want a gay MP in Reigate.

He told the Guardian: "I would not be happy if we had a gay candidate here – I would always go for a candidate who had a normal background. Our current MP [Blunt] is happily married with two children."

Another senior figure in the local association said that many elderly people in Reigate felt uncomfortable about Blunt's sexuality, saying: "You can't change people who are 75, 85, 90. They've got their own views from years ago."

The Tory said Blunt's announcement in 2010 had played no part in the decision to force a vote but added: "He did vote with the prime minister on gay marriages and a lot of people – we are quite old fashioned – didn't like that one bit. But nothing to do with him being gay."

The office holder said Blunt faced a vote because he had neglected the constituency. "I hope that when he sees the count, and he sees how many people are voting against him, it might make him pull his socks up and do what he should be doing.

"He doesn't attend council meetings and he doesn't attend country council meetings and he doesn't help one on the local issues compared to Mr [Chris] Grayling next door. He attends everything and he is a much higher MP."

Blunt told a recent constituency rally that victory was essential for the image of the party nationally. "Your backing will make an emphatic statement about the values of our community and party that will do credit to both," he said.

In a letter to association members last month, Blunt said he enjoyed the support of his family. He wrote: "I accept that speculation, cheerful or otherwise, about the private life is something public figures must expect, but I am lucky enough to continue to enjoy the love and support of Victoria and my children, Claudia and Freddy, and to finally be at ease with myself.

"Your backing will make an emphatic statement about the values of our local community and our party, specifically that we are tolerant and reasonable people, who judge others fairly on their ability to do the task in hand."

Blunt secured an overwhelming victory of around five to one in the postal ballot. A Tory source said: "We are very pleased. Crispin Blunt is a great champion for local issues."

Blunt welcomed the result but criticised the "irrational and unexpected action" of the association's executive council to force a postal ballot.

Blunt's statement said the row "came without warning that there was any aspect of my performance as MP that was terminally inadequate, and, in the absence of any serious issue around my performance as MP, brought the local party into disrepute. Happily the wider membership has rescued the reputation of Reigate and the Conservatives by a thumping margin".

He added: "Those members of the executive council who voted against my candidacy in the absence of a cogent reason they could publicly present and having now been so convincingly contradicted by the wider membership must ask themselves how they can best assist uniting and reinvigorating a party which is overwhelmingly united around my candidacy."

• This article was amended on 22 November 2013 to remove a stray and confusing section of text that had been included in a paragraph about Tony Collinson because of an editing error.