British Prime Minister Boris Johnson has married his fiancee Carrie Symonds in a low-key ceremony planned in strict secrecy.

The pair exchanged vows on Saturday in London’s Westminster Cathedral in front of a small group of close friends and family.

Downing Street would not comment on the reports, but Tory MPs and ministers sent their congratulations to the couple.

One No 10 aide said: “I have been strictly told not to comment.”

The Sun reported that even senior Downing Street aides were unaware the couple were about to tie the knot on Saturday.

The couple announced their engagement – together with the news that they were expecting their first child – in February 2020.

It is Mr Johnson’s third marriage, having finalised his divorce from second wife Marina Wheeler in 2020.

He and Ms Symonds have a son, Wilfred, who was born in April 2020.

The ceremony at the Catholic cathedral was carried out by Father Daniel Humphreys, who had given the couple pre-marriage instructions, and baptised Wilfred in 2020, The Sun reported.

Britain’s Prime Minister Boris Johnson and Carrie Johnson pose together for a photo in the garden of 10 Downing Street after their wedding. Photo: AAP

Cathedral cleared

Shortly after 1.30pm, the cathedral was suddenly cleared of visitors, with staff saying it was going into lockdown, the newspaper said.

Half an hour later, a limousine carrying the bride swept into the piazza outside the main west door.

Ms Symonds wore a long white dress but not a veil, while Mr Johnson was described as wearing a “very dapper” suit.

Congratulations and all that, but a serious question for the Catholic Church: how did this twice-married serial adulterer get a Catholic wedding? https://t.co/QICz1Lc9KE

— Tim Walker (@ThatTimWalker) May 29, 2021

The ceremony meant Mr Johnson became the first prime minister to marry in office since Lord Liverpool married Mary Chester in 1822.

The marriage came just days after the couple were said to have sent save-the-date cards to family and friends for a celebratory event on July 30, 2022.

Weddings in England are subject to strict coronavirus restrictions.

Dancing is advised against due to the increased risk of transmission, except the couple’s traditional first dance.

Mr Johnson’s father, Stanley, was spotted in Downing Street after the ceremony, while guests and musicians were seen leaving No.10 on Saturday night.

Wedding and woe

The wedding came at the end of a difficult week for the Prime Minister in which his former aide Dominic Cummings branded him unfit for office.

Cabinet minister Therese Coffey sent her congratulations to the couple “on your marriage today”.

Northern Ireland’s First Minister Arlene Foster tweeted: “Huge congratulations to Boris Johnson & Carrie Symonds on your wedding today.”

But former Labour frontbencher Jon Trickett said the wedding was “a good way to bury this week’s bad news” on Mr Cummings’ testimony, the spread of the Indian coronavirus variant and the row about funding of the PM’s Downing Street flat.

Fellow Labour MP Tonia Antoniazzi suggested the “emergency marriage plan” was an attempt to “deflect from negative press” from Mr Cummings.

“They know he won’t be able to plan one in Chequers (the British prime minister’s official residence) cos he won’t be PM next year,” she said.

-AAP