The marriage law was the final victory in a long battle that has already secured the same age of consent as heterosexuals and the right to adopt - but it was still a day many thought would never come.
"When I came out in 1983 when I was 20, the age of consent was 21. My first sexual relationship was with another 20-year-old, and we could have both been sent to prison," said Matthew Toresen, a community worker from Northampton in central England.
Toresen, now 51, married his long-term partner Scott Maloney, 45, on the first day that gay marriages were possible under the law.
The couple have spent years campaigning for gay rights, from lowering the age of consent to tackling discrimination in the military, and describe gay marriage as "the last hurdle."
Civil partnerships were introduced in England and Wales in 2005, effectively giving gay couples the same legal rights as heterosexuals.
But campaigners insisted that only full equality would do, a principle that the majority of the public accept - there were no mass protests in Britain of the kind seen in France last year when same-sex marriage was legalized.
Gay marriage was approved by the British parliament last year with the support of Prime Minister David Cameron, despite vocal opposition from some members of his Conservative party.
The Church of England also objected, and was given an exemption from conducting same-sex ceremonies.
By Ruchi Singh
reporter
Park Sae-jin
swatchsjp@ajunews.com