It is but a few short years since the prospect of a Conservative Prime Minister backing gay marriage at a Tory party conference was unimaginable. It is gratifying that so much has changed.

It was David Cameron himself who broke the mould, declaring in his first conference speech as Conservative leader that marriage means something "whether you're a man and a woman, a woman and a woman, or man and another man". As Prime Minister, he went a step further yesterday, referring proudly to a consultation on gay marriage, and hinting that if Tory plans to recognise marriage in the tax system go ahead, such measures will apply to all unions, gay or otherwise.

That the same legal status should be accorded to gay and straight relationships is an argument that hardly needs to be made. And although this newspaper is wary of tax breaks for marriage, such a policy should at least apply to all.

Equally laudable were Mr Cameron's efforts to couch gay marriage in terms of the traditional Conservative value of commitment. "I don't support gay marriage despite being a Conservative. I support gay marriage because I'm a Conservative," he said.

It will take more than a couple of speeches to persuade the Tory right to abandon its prejudices, if it is possible at all. But it is to Mr Cameron's credit that he is trying, even more so that he is pressing ahead regardless.