Ben and Jerry's have teamed up with gay rights organisation Stonewall to campaign for the legalisation of same sex marriage in the UK, with the government's formal consultation on the issue beginning today.

The carton for the new flavour features two happily married grooms atop a rainbow cake of tolerance, and will be available in the coming weeks.

On the brand's website they're urging people to write to their MP about the issue, providing a template letter and showing people how to track down their member of parliament.

"Social justice is at the core of our values," said a Ben and Jerry's statement.

"Since our humble beginning 34 years ago, Ben & Jerry's has been an advocate for equal rights.

"Did you know we were one of the first companies in the US back in 1993 that widened our health & employment benefits umbrella to recognise unmarried domestic partners regardless of their sexual orientation?"

"If you think that Civil Partnership is the same as marriage, think again! Show your support and help convince members of parliament that it's time to say 'I do' to same sex marriage!"