Fashion guru Mary Portas and journalist Melanie Rickey became the first couple in the UK to have their civil partnership converted to a same sex marriage.

The couple were already in a civil partnership but fashion entrepreneur Ms Portas surprised Ms Rickey by taking her to Westminster City Hall in Victoria Street, Victoria, to convert their partnership to marriage at 12.01am today (December 10) - one minute after civil partnership conversions to gay marriages became legal in the UK.

Westminster superintendent registrar, Alison Cathcart, presided over the landmark conversion, as she did with the couple’s civil partnership.

Fashion journalist Ms Rickey, 41, said: “I thought we were out looking for art galleries but when we started driving up and down the same street a couple of times I started getting a bit suspicious. When we turned up outside Westminster City Hall I guessed what was going on. I couldn’t think of a better surprise. It is so special we were able to be the first couple in the country.”

Ms Portas, 54, added: “It was wonderful when we had our civil partnership but I wanted to take that final step and get married and what better way to do it than be the first. We have three children together and there is such a deep rooted commitment to being married, it just felt right.

“Tonight was absolutely magical and meant so much to us that we could have Alison and Mark, who conducted our civil partnership, to preside over our marriage. Our last ceremony was very different, with a much wider extension of friends and family. Tonight was very intimate with just the children, our PA and our close friend Emma who is also Horatio’s godmother, it was perfect really.”

The Mary, Queen of Shops presenter said she had been planning the wedding for months and had both their rings rebuffed but had kept it secret from most of their friends and family

She added: “We called Mel’s mum minutes before the ceremony and told her we were getting married. Now we are just going into the country to relax and hopefully do nothing for a couple of days – not that that comes easy to us.”

Westminster Register Office conducted the most civil partnerships in the country in 2005, the first same sex marriage in March this year and now the first conversion of civil partnership to same sex marriage.

Steve Summers, Westminster Council’s leisure chief, said: “We fully support gay marriage, and this just goes to show that whoever you are, and wherever you are from, Westminster is the best place to get married in the UK.”