Gay marriage on the horizon: The bill is expected to easily pass in the Commons although it could face obstacles in the Lords.

Gay marriage: Modernising Tories go to war

Gay marriage: Modernising Tories go to war

The Conservative party was in danger of going to war with itself today, after a group of prominent modernisers clubbed together to support David Cameron's move toward gay marriage.

The plan, which would allow churches to hold gay marriages if they wanted to but legally protect those who do not, is opposed by at least 130 Tory MPs and a handful of Cabinet ministers.

"Marriage should be open to all, regardless of sexuality," a letter to the Sunday Telegraph signed by 19 senior Conservatives stated.

"We recognise that civil partnerships were an important step forward in giving legal recognition to same sex couples. But civil partnerships are not marriages, which express a particular and universally understood commitment."

London mayor Boris Johnson and education secretary Michael Gove are signatories to the letter, along with Catholic transport secretary Patrick McLoughlin.

The group was formed by Nick Herbert, former police minister, who is in a civil partnership.

Foreign Office minister Alistair Burt, prominent backbencher Nicholas Soames and Scottish Tory leader Ruth Davidson, who is a lesbian, are also supporters.

The support group will be a welcome relief to the prime minster, who has been attacked as arrogant and out-of-touch by several of his MPs after he redoubled his efforts to get gay marriage passed, with added measures to allow the ceremonies to take place in religious buildings.

Cameron has been reassured by polling showing widespread public support for the move, but it is likely the sections of the population most opposed to the move – such as older voters – would disproportionately come from Tory-supporting ranks.

The bill legalising gay marriage should come before the Commons before Easter next year, with the first ceremonies taking place in 2014.

MPs will be given a free vote on the plans.