London (CNN) Boris Johnson and his girlfriend Carrie Symonds moved into Downing Street on Monday, the new UK prime minister's spokeswoman said.

There had been speculation over whether Symonds, who has quickly become a mainstay in British tabloid newspapers, would join Johnson at the residence. The PM's office had told CNN last week it did not know whether the pair would be living together.

The move makes Johnson the first prime minister in living memory to live with an unmarried partner in Number 10.

His divorce from his second wife, Marina Wheeler, with whom he has four children, is yet to be finalized. The pair announced they were splitting after 25 years of marriage last September, shortly after which Johnson's relationship with Symonds was confirmed.

Interest in the couple was heightened after details of an altercation between the pair at Symonds' flat were reported by The Guardian last month.

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