It's being billed as France's "marriage of the century". The two grooms will wear suits, the vows will be simple and refer to two "spouses" but the normal wedding room at Montpellier town hall won't be big enough for the 200 friends and family, 300 guests from activist associations, 130 journalists from across the world and one government minister present so it will decamp to a larger function hall. At 5.30pm in the southern French city of Montpellier, which describes itself as France's most gay-friendly place, after months of divisive national wrangling, numerous street demonstrations, 172 hours of heated parliamentary debate, and a warning of a 30% rise in homophobic acts, Vincent Autin and Bruno Boileau will become the first same-sex couple to marry in France. After the gay marriage and adoption law was passed 10 days ago, Autin, 40, a gay rights activist who works for the Montpellier tourist office, and Boileau, 30, a civil servant, quickly published the banns, booked the outfits, organised the rings, the DJ, the car and the childcare for guests bringing children. They had long planned to be the first couple to marry when France became the 14th country in the world to legalise same-sex marriage – the key social reform of the Socialist François Hollande's presidency. Last September, the women's minister, Najat Vallaud-Belkacem, on a political visit to Montpellier, had asked Autin if he wanted to be the first groom. He immediately called Boileau who instantly said yes. The couple had been living together for seven years.