The Isle of Man has just approved the introduction of same-sex marriage. The Manx Legislative Council has passed its Marriage and Civil Partnership (Amendment) Bill.

Agreements to bring same-sex marriage into law have now been made in England, Wales, Scotland, the Republic of Ireland and both the Bailiwick of Guernsey and the Bailiwick of Jersey. That makes the Isle of Man the last place in the British Isles to agree to introduce it.
You can read more here.