And it wasn't even close:
MPs have voted for the gay marriage bill by 400 votes to 175 - a majority of 225. Such a large majority probably increases the chances of the bill being able to get through the House of Lords this year, without the government having to rely on the Parliament Act to push it through in 2014. More than half of the Tory MPs who voted chose to oppose gay marriage. Initial figures suggest that 139 Tories voted against, and only 132 voted for. Technically this is not a rebellion, because it was a free vote. But it is a severe embarrassment to David Cameron.
History will consider the Tories who voted no to be a much more severe embarrassment.