The rainbow flag has been hoisted over Whitehall to coincide with London's gay pride celebration this weekend.
The symbol of lesbian, gay, bisexual and transgender pride is fluttering over the Cabinet Office where deputy prime minister Nick Clegg has his office.
The Lib Dem leader said the move was a "small but important emblem that the Government and this country are behind equal rights".
''I'm absolutely delighted that, with a little bit of persuasion and determination, we've been able to fly the rainbow flag for this weekend's festivities. I hope this is the start of a new era of pride across the historic Whitehall village," he said.
Yesterday Clegg said he thought churches and other religious premises should be allowed to host gay weddings.
The deputy prime minsiter stressed that while he did not want to force any religious group to marry same-sex couples, he saw no reason to stop churches from doing so if they chose to.
His comments go beyond the proposals to legalise civil marriages for homosexual men and lesbians, set out in a government consultation paper which has sparked a furious reaction from some religious groups.
The proposals, backed by prime minister David Cameron, envisage same-sex civil marriage ceremonies in a register office or approved premises but no change to religious marriages, which can only take place between a man and a woman.
Under the proposed reforms, religious premises would continue to be allowed to host civil partnership registrations on a voluntary basis, but without any religious content.
Clegg told the Evening Standard: "This is a personal view at the moment, but I think that in exactly the same way that we shouldn't force any church to conduct gay marriage, we shouldn't stop any church that wants to conduct gay marriage.