Boris Johnson becomes fourth Prime Minister to welcome baby to Downing Street in 170 years

Prime Minister Boris Johnson's partner Carrie Symonds has given birth to a "healthy baby boy" (Picture: AFP via Getty Images)

Boris Johnson is the fourth Prime Minister to welcome a baby to Downing Street in 170 years.

Mr Johnson, 55, and Ms Symonds, 32, announced the arrival of their baby boy on April 29 2020.

The news of the birth comes just weeks after the PM was discharged from intensive care where he had been battling coronavirus.

The child is the fourth to be born to a Prime Minister while in Downing Street, with Tony Blair and David Cameron both adding to their families while in Number 10.

But that is a relatively recent trend, with a gap of more than a century before Leo Blair became a Downing Street baby.

David Cameron, Britain's Prime Minister at the time, left, arrives at his hotel with his wife Samantha and their few week old baby daughter Florence in 2010 (AP)

Tony Blair’s wife Cherie gave birth to son Leo in May 2000, three years after her husband’s first election victory.

Mr Blair’s youngest son was the first child legitimately born to a serving prime minister for more than 150 years.

In Cherie’s memoirs, Speaking For Myself, the QC revealed Leo was conceived during a visit to Balmoral, the Queen’s residence in Scotland.

Leo was born at Chelsea and Westminster Hospital in London on May 20, 2000 at 00.25am, weighing 6lbs 12oz.

He joined sister Kathryn and brothers Euan and Nicky in the Blair sibling ranks.

David Cameron and wife Samantha welcomed daughter Florence in 2010.

Tony Blair watched by his wife Cherie, kisses his baby son Leo outside 10 Downing Street in 2001 (AP)

David Cameron and his wife Samantha welcomed daughter Florence Rose Endellion Cameron into the world in 2010.

Mr Cameron had only formed a coalition government with the Liberal Democrats three months prior to her being born, with the general election that year producing a hung parliament.

Florence was delivered by Caesarean section at the Royal Cornwall Hospital in Truro while the Camerons were on their summer holiday.

The last baby born to a prime minister before Leo and Florence was 170 years ago, to Lord John Russell, leader of the Whig Party.

Lord John Russell was Prime Minister twice, the first time from 1846 until 1852 and the second time from 1865 to 1866.

Lord Russell, had six children in total, and was the grandfather of philosopher Bertrand Russell.

During his first tenure as Prime Minister he had two sons with his wife Lady Frances Elliot-Murray-Kynynmound, the first, George, in 1848 and the second, Francis, in 1849.

The baby is Ms Symonds’ first child, while Mr Johnson is known to have fathered five previously.