In the end, the location of Britain's first civil partnership was decided by a quirk of regional bureaucracy. The registration period for marriages is shorter in Northern Ireland than in the rest of the UK. So at 10am yesterday, amid the classical splendour of Belfast City Hall, the union of Grainne Close and Shannon Sickels became Britain's first "gay marriage". This becomes the first homosexual relationship to be recognised in the eyes of UK law.

Many more are to follow. There will be hundreds of similar ceremonies across the country in coming days, as couples who filed their applications as soon as the Civil Partnerships Act came into force make the trip to their local registry offices. From today, homosexual relationships will be recognised in Scotland. And tomorrow, ceremonies will take place across England and Wales. One union likely to command a good deal of attention will be the marriage of David Furnish to his long-term partner Sir Elton John at the Windsor Guildhall. By the end of the week it is estimated that over 700 gay marriages will have taken place.

We should not forget - amid all the fluttering confetti - what a difference these ceremonies will make to the lives of thousands of same-sex couples. This week marks the culmination of decades of campaigning by gay rights activists for homosexuals to be given the same pension and inheritance rights as married heterosexuals. Until now, thousands of homosexuals have been faced with unjust financial penalties upon the death of their partners.

Inevitably, not everyone is happy. Yesterday's ceremony in Belfast was marred by a nasty protest by religious zealots who labelled the historic union of Ms Close and Ms Sickels an "abomination". And, as we reported yesterday, the threats sent to a prominent gay couple - apparently by British soldiers serving in Iraq - is a reminder that a vile hatred towards homosexuals still exists in Britain. A minority of gay campaigners are also unhappy, arguing that civil partnerships are simply "second-rate" marriages.

In fact, though, opposition to civil partnerships has been distinctly muted, from both left and right. Perhaps the backlash has not really begun. But we prefer a more optimistic view. This absence of fuss is more likely to indicate that the concept of gay marriage is no longer controversial. Allowing homosexuals who live in a loving relationship to make a legal commitment to each other is now widely regarded as a benign development.

The Civil Partnerships Act has been one of the unequivocal successes of Tony Blair's government. The response to today's gay marriages is a welcome sign that Britain is becoming a more liberal and civilised place.