Boris Johnson and his fiancee Carrie Symonds have named their baby boy Wilfred Lawrie Nicholas Johnson.
The names are a tribute to their grandfathers and two doctors who treated Mr Johnson while he was in hospital with coronavirus, Ms Symonds wrote in an Instagram post.
She posted a picture of herself with the baby, who was born on Wednesday.
And she thanked staff at University College London Hospital, adding: “I couldn’t be happier. My heart is full.”
The birth came just weeks after Mr Johnson was discharged from intensive care at another London hospital following treatment for coronavirus.
Ms Symonds wrote on Saturday that their son shares his first name with the prime minister’s grandfather, and the first of his middle names, Lawrie, with her own.