Northern Ireland will be brought into line with the rest of the UK after MPs approved legislation to reduce the age of consent in the province from 17 to 16.
The Sexual Offences (Northern Ireland Consequential Amendments) Order is expected to be on the statute books within the next month.
The Conservative party abstained during the Commons vote on Tuesday, with four of their MPs (Philip Hollobone, Peter Bone, Ann Winterton and Sir Nicholas Winterton) voting against.
Cabinet Ministers Ruth Kelly, Andy Burnham and Des Browne were among those who voted for the order.
The Minister of State for Northern Ireland, Paul Goggins, said last month:
“We are certainly not encouraging 16-year-olds to engage in sexual activity.
“What this is about is defining the age at which a criminal offence takes place even when consent is given.
“Where there is evidence of abuse or exploitation, then the new law will deal with that much more stringently, with many offences designed to protect right up to the age of 18.”
In both Northern Ireland and the Republic of Ireland at present the age of consent for both gay and straight sex is 17.
The BBC reported that some politicians in the province think that the one year age difference with the Republic would encourage sexual predators to cross the border.
Members of the Northern Ireland Assembly do not have jurisdiction over criminal justice matters at present, though there are plans to extend their powers.
That could lead to the lower age of consent being overturned.
In February, Assembly members voted to retain the current age.
The province is generally more conservative on sexual matters than the rest of the UK. Unionist politicians in particular have opposed gay rights.
The Democratic Unionist Party, who are in government with Sinn Fein in Northern Ireland, are likely to fight to retain the age of consent at 17.
The party has been consistently hostile to gay rights legislation imposed by the British government since 1997.