LONDON -- The patter of tiny feet is coming to Downing Street.

British Prime Minister Boris Johnson revealed Saturday that he and his girlfriend, Carrie Symonds, are engaged to be married and expecting a baby in the early summer.

A wedding date wasn't announced.

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Johnson, 55, and Symonds, 31, made history as the first unmarried couple to openly live together at the British prime minister's official London residence when they moved in last year.

Symonds, a conservationist and former communications chief for the Conservative Party, which Johnson now leads, was romantically linked to Johnson when Theresa May still served as prime minister.

Symonds said in an Instagram post she felt "incredibly blessed."

She said she and Johnson got engaged at the end of last year “and we've got a baby hatching early summer.”

Johnson has four children with his second wife, Marina Wheeler, a lawyer he married in 1993. They announced their separation in September 2018 and said they planned to divorce. Johnson has fathered at least one other child.

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The wives of two of the last four British prime ministers, David Cameron and Tony Blair, had babies while their husbands were in office.