A survey carried out by the Williams Institute has predicted that legalising gay marriage across America could prove a lucrative move.

The institute, which carries out research for the University of California, has said that if gay marriage were made legal in every state, about half of all cohabiting gay couples would get married. That would mean around 390,600 weddings.

Although gay couples tend to spend about 34 per cent less on weddings that their straight counterparts, the revenue from catering, photography and gifts would still be considerable.

Based on the details given by the Williams Institute, the news agency Forbes estimates that if half of all same sex couples did get married, the wedding industry would make about $9.5 billion (£5.8 billion).

Currently, same-sex marriage is only legal in Massachusetts, Connecticut, Maine, Vermont, Iowa and New Hampshire.