Heterosexual couples can form civil partnerships as an alternative to traditional marriage in the British Isles for the first time after a change in the law on the Isle of Man.

New legislation which has just come into force on the Island - a crown dependency separate from but closely tied to the UK - will create new pressure in mainland Britain for straight couples to be allowed to form legally recognised partnerships.

But it also creates a new legal grey area in other parts of Britain, with uncertainty over how opposite sex couples in civil partnerships under Manx law will be recognised, if at all.

It comes just months before a crucial legal battle over the current law in England and Wales which restricts civil partnerships to gay and lesbian couples despite the legalisation of same-sex marriage.