Why Cameron promoted anti-gay marriage MPs during reshuffle

43 per cent of those promoted by the Prime Minister voted against the Marriage (Same Sex Couples) Bill last year

Anti-gay marriage protesters outside Parliament on 21 May 2013 (AFP)

David Cameron promoted a string of MPs who voted against same-sex marriage in an apparent attempt to stem the mass desertion of Tory grassroots members over the issue, new research shows.

Analysis of the Conservative associations accounts, published by the Electoral Commission, shows a revolt over gay marriage was one of the major reasons why local party membership fell over the past year.

In his reshuffle earlier this month, 43 per cent of MPs – 17 out of 42 – promoted by the Prime Minister voted against the Marriage (Same Sex Couples) Bill last year. While this proportion is similar to the amount of Tory MPs across the board who voted against the policy, it is remarkable that Mr Cameron promoted so many who effectively rebelled against the party line.

While Tory party membership has halved since Mr Cameron became leader, associations are reporting a dramatic drop in numbers as many switch to Ukip. The latest annual accounts for the Conservative associations report same-sex marriage as a major factor.

In a survey of 16 associations where membership subscriptions have fallen, same-sex marriage was cited as a reason in half of those constituencies, while national party policy was blamed in the other half.

Accounts for Bracknell Conservative Association, where sitting MP Phillip Lee voted in favour of same-sex marriage, reported: "The membership situation was adversely affected by the... controversial 'gay marriage' bill which prompted a number of resignations."

In Calder Valley, whose MP Craig Whittaker voted against gay marriage, the association reported: "Membership has decreased this year due to a number of factors, the main feedback we have received related to the coalition debate and vote about gay marriage."

The shadow equalities minister, Gloria De Piero, said: "David Cameron promised change, but it seems he's deserted equality as an objective. His party is in rebellion at same-sex marriage, and rather than showing leadership he's chosen to reward and promote those opposed to marriage equality."