The chief executive of ComRes Andrew Hawkins has accused David Cameron of making misleading statements over polling data regarding equal marriage.

The Spectator has exclusively seen correspondence between the prime minister and Mr Hawkins over the issue.

Last month, PinkNews.co.uk revealed that the PM had replied to a letter by the former Welsh Secretary Cheryl Gillan after the Tory MP expressed her concerns about the government’s marriage reforms.

David Cameron used polling data from ComRes  as part of his argument to claim that the policy would benefit the party.

However, according to the Spectator, in a letter to Mr Cameron, Chief Executive Andrew Hawkins accused the PM of wrongly interpreting his polling organisation’s data and said:

“Your letter of 19 October 2012 to The Rt Hon Cheryl Gillan MP states that a recent poll by ComRes found that 10 percent of current Conservative voters say that the policy [to legalise same-sex marriage] would make them ‘less likely to vote Conservative’ compared with 7 percent saying it would make them ‘more likely to vote Conservative’.

I should like to put the record straight because the wrong figures have been quoted. Your figures relate to whether current Conservative voters are more likely to vote Labour, not Conservative, as a result of the policy. The correct figures are that 19 percent (of current Conservative voters) are more likely to vote Conservative, while 11 percent are less likely to do so.’

However, this is to miss the more important point from the poll which shows both that the party loses more votes than it gains as a result of the policy, and that former Conservative voters are especially less likely to return to the fold”.

In August, Lord Ashcroft, one of the Conservative Party’s most influential supporters and a former deputy chairman, said on the ConservativeHome website that dropping equal marriage could damage the party’s electoral fortunes.

“In political terms, ditching gay marriage would probably be more likely to put off joiners and considerers – whom we need if we are to win a majority – than it would to win back defectors”.

On Monday, Chancellor George Osborne warned the Conservative Party that ditching its support for equal marriage could cause a catastrophic defeat at the 2015 general election.