Opponents of gay marriage will be seen by history in the "same light" as those who once opposed mixed-race partnerships, one of the driving forces behind Britain's changing equality laws claims today.
Richard Reeves, until this summer Nick Clegg's director of strategy who helped draw up the Coalition's proposals to legalise same-sex marriages, said the Government needed to "stand up to the forces of conservatism".
He said he disagreed with Mr Clegg for recalling a press release calling opponents of gay marriage "bigots". "Here's the thing: they are bigots," he wrote in the New Statesman. "In the end, the only reason to deny a gay couple the right to marry is a belief that their relationship is in some way inferior to a heterosexual one. That's bigotry."
Mr Reeves added: "I have no doubt that the opponents of same-sex marriages will be seen, in fairly short historical order, in the same light as those who opposed mixed-race marriages."
His comments came as Independent Voices launched a campaign to ensure gay marriage is put on the statute book.
Next month, anti-gay marriage activists plan a show of strength at the Conservative Party Conference. They have booked a 1000-seat venue in Manchester which they hope to fill with Tory peers, MPs and supporters.
'Independent Voices' is putting forward a manifesto calling on our politicians to start legislating on equal civil marriage rights. Sign today at independentvoices.com