Boris Johnson moves into 10 Downing Street with girlfriend Carrie Symonds

British Prime Minister Boris Johnson on Monday moved into 10 Downing Street with his girlfriend Carrie Symonds, putting an end to speculation whether she would join him at his new residence.

The new British Prime Minister and his partner occupied the large flat above 11 Downing Street, which is occupied by Chancellor of the Exchequer, Sajid Javid, despite having a bigger family with four young children, The Irish Times reported.

Johnson's deputy spokeswoman was quoted as saying earlier that the couple would be moving in officially today (Monday/local time), with Symonds taking up residence there with him.

There had been speculations that the unmarried partner of Johnson might not move with him in 10 Downing Street after she was seen moving furniture into a house in southeast London with her mother.

Johnson and his partner have not been seen publicly together since they were recorded by a neighbour in the Camberwell area of London having a late-night brawl just before the elections.

After the row, newspapers printed an apparently old photograph of the couple that seemed to have been released by Johnson's campaign team as part of its Public Relations strategy.

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

After reports that Johnson had asked for new furniture to be bought, his spokeswoman said, "There will not be any additional cost to the taxpayer of her [Symonds] living there."

Johnson comfortably won the Conservative Party leadership election last week and was appointed Prime Minister last Wednesday.

Symonds has also enjoyed a successful political career, working as part of the campaign team that helped to get Johnson re-elected as mayor of London in 2012.