Treasury Minister Angela Eagle entered into a civil partnership with Maria Exall in Southwark today.
The Labour MP for Wallasey, who was named the fourth most powerful LGBT person in Britain by PinkNews.co.uk, has been in a relationship with Ms Exall for the past 18 years.
She has become the first lesbian MP to enter into a civil partnership.
Ms Eagle, who was actively involved in securing Labour’s Civil Partnership Acct in 2004, will later attend a celebratory party at the Bread and Roses pub in Clapham.
Ms Eagle’s twin sister, fellow MP, Maria said: “It’s been great, everyone was very pleased and they are very much in love.”
The news of the Minister’s intended nuptials was revealed by the Deputy Leader of the Labour party, Harriet Harman, during a question and answer session at the TUC conference earlier this month.
Ms Eagle told PinkNews.co.uk: “Maria and I met in Peckham Labour Party 18 years ago, and so Harriet has more right to announce it than nearly anyone.”
The minister who has represented Wallasey since 1992, came out as a lesbian soon after the 1997 election.
In June 2007 she was appointed to the government by Gordon Brown, in the newly-revived position of Exchequer Secretary to the Treasury.
She is a member of Labour’s governing body, the National Executive Committee.
Health Minister Ben Bradshaw became the first MP to hold a civil partnership ceremony two years ago.
Shadow business secretary Alan Duncan became the first Conservative MP to hold a civil partnership ceremony in July.