Updated at 15:40 BST.

A ComRes poll announced by equal marriage opponents the Coalition for Marriage and Christian Institute has revealed that, for most voters, the government’s proposals are not enough to sway them to or from a political party.

Across the population, 10 percent of voters said they would be more likely to choose the Tories as a result of Prime Minister David Cameron’s plans to equalise civil marriage for gay and straight couples.

13 percent said they would be less likely to vote Conservative as a result, according to ComRes, who polled over 2000 people across the UK.

The majority of respondents, 56 percent, said it was a non-issue. 19 percent would vote Tory and 37 percent would not, regardless of the plans.

55 percent of voters similarly said the proposals had no effect on whether or not they would vote Labour or Liberal Democrat, whose leaders also support equal marriage.

The poll was originally said to have been commissioned by the Coalition for Marriage. While this report was being written, ComRes changed the name of the body which commissioned the poll on its website to the Christian Institute.

Neither the Christian Institute nor the Coalition for Marriage could say immediately which of them had commissioned the survey. ComRes advised PinkNews.co.uk to list the Christian Institute. ComRes has since told PinkNews.co.uk the Coalition for Marriage was listed in an internal error.

The poll was released at the weekend as being commissioned by the Coalition for Marriage the day after the government announced it would be investigating the Catholic Education Service’s letter to schools asking them to promote the Coalition for Marriage’s anti-equality petition to students as young as 11, which had been uncovered by PinkNews.co.uk days earlier.

Announcing the results of the poll, the Coalition for Marriage and Christian Institute claimed the government “could lose up to 30 Parliamentary seats and 1.1 million votes” as a result of civil marriage equality.

The Coalition for Marriage said the results were “devastating” for the government. Dr Colin Hart, a director of the anti-marriage equality campaign and of the Christian Institute, said the survey contributed to a perception of the move as a “major vote loser”.

No one from the Coalition for Marriage was available to talk to PinkNews.co.uk about how the 1.1 million voters figure had been calculated today, but a representative did repeat the campaign’s claim that for every vote won the move would cost the Conservatives three.

The claim that marriage equality would cost three votes for each vote won appears to have been extrapolated from a particular group: self-identifying former Conservative voters who said they already no longer intended to vote Conservative.

The former Tory voters were asked whether the government’s plans made them more or less likely to return to the party. 11 percent said it made them more likely to return. 32 percent said it strengthened their pre-existing decision not to vote Tory.

For every one of the former Tory voters attracted back to the party by the policy, therefore, three voters who said they were already alienated from the party were less likely to return.

PinkNews.co.uk put it to the Coalition for Marriage that if those voters had already abandoned the party for other reasons, marriage equality did not lead to a net loss of voters but, all things being equal, actually won back 10 percent of lapsed supporters, making the policy a vote winner among former Tories. The query was noted.

Seven percent of the Liberal Democrat voters at the general election in 2010 who had since dropped support for the party said they were similarly likely to return to the junior coalition partner as a result of the policy. 10 percent said they were less likely to return.

For those respondents who did vote Conservative in the 2010 election, 15 percent were more likely to vote Tory as a result of the plans, 18 percent were less likely and the majority, 53 percent, said marriage equality made “no difference” to them.

The Coalition for Marriage said the Conservatives could lose up to 1.1 million votes as a result of the policy. PinkNews.co.uk has asked the Coalition for Marriage to clarify how it reached the figure and has asked ComRes how the results should be interpreted. The accuracy of the poll itself is not in question.

Although 18 percent of people who voted Tory in the 2010 general election said they were less likely to vote Tory now due to the civil marriage equality plans, 7 percent of that year’s Labour voters and 10 percent of the Liberal Democrats’ voters said they were inclined to switch allegiance to the Conservatives as a direct result.

Using figures from the 2010 general election, if 18 percent of Tory voters abandoned the party and were replaced by 7 percent of Labour voters and 10 percent of Liberal Democrat voters, it would appear to result in a net loss to the Conservative party of a maximum number nearer 400,000 voters, or 4 percent.

These figures do not reflect current voter intentions, however, as support for the Tories has fallen while support for Labour has risen following the general election of 2010, and the poll did not ask voters whether they would definitely change their voting preference.

Respondents were asked how they felt about the statement: “Does the Coalition Government’s announcement that it plans to redefine marriage to include same-sex relationships make your more likely or less likely to vote [Conservative, Labour or Liberal Democrat] or does it make no difference?”

London’s Evening Standard came out in support of marriage equality last night, saying the prime minister should “stick to his guns” on the issue, saying the “challenge for marriage today is not that gay couples want it but that so many couples are not tying the knot at all”.

To view the poll results, click here.

Update: ComRes has told PinkNews.co.uk the survey was commissioned by the Christian Institute and the Coalition for Marriage was named in an internal error.