Carrie Symonds and Boris Johnson’s son Wilfred is the third baby to be born & live at Downing Street in 20 years

BORIS Johnson's baby is the third in 20 years to be born while his parents are living at Downing Street.

The Prime Minister and his fiancee Carrie Symonds, 32, revealed today they have called their first child Wilfred Lawrie Nicholas, and shared an adorable first photo.

Follow the Boris Johnson baby live blog for latest news & updates

In a statement released on Wednesday April 29 , a spokesman said: "The Prime Minister and Ms Symonds are thrilled to announce the birth of a healthy baby boy at a London hospital earlier this morning. Both mother and baby are doing very well.

“The PM and Ms Symonds would like to thank the fantastic NHS maternity team.”

Boris, 55, may be the third PM in two decades to welcome a baby while in office.

But Carrie is the only woman to become a first-time mum with a serving PM. Their son is Boris' sixth child.

David Cameron

Former Tory leader David Cameron was the last British leader to welcome a baby in office.

His wife Samantha Cameron gave birth to their fourth child Florence Rose Endellion in August 2010.

Cameron also became the first British PM to take statutory paternity leave, as it was only introduced in 2003.

Tony Blair

When Tony and Cherie Blair welcomed baby Leo in 2000, he became the first legitimate child of a serving PM in 150 years.

Like the Camerons, Leo is the Blair's fourth and youngest child.

In her 2008 memoir Speaking for Myself, Cherie revealed Leo was conceived during a stay at the Queen's Scottish retreat Balmoral.

Lord John Russell

Before Blair, Liberal PM Lord John Russell welcomed two of his six kids while in office.

He and wife Lady Frances Elliot-Murray-Kynynmound had sons George in 1848 and Francis in 1849.

Carrie is said to have given birth weeks early at a London hospital, with Boris by her side, just days after her fought for his life in intensive care. Get the latest on the birth here.