Labour leader Ed Miliband and his partner Justine Thornton have announced the birth of their second child.
The boy arrived late on Sunday night, weighing 8lb 3oz, according to a party spokesman. Both mother and baby were said to be doing well after the birth at University College Hospital in London.
Speaking to reporters outside the hospital, the Labour leader said: "We didn't know he would come quite as quickly as he did. Justine did absolutely brilliantly."
He said of his new son: "He's really gorgeous, he looks a bit like me. As I say, we are absolutely delighted."
Asked if the couple had decided on a name, Mr Miliband joked that he had his own views but "it's still being signed off".
He said: "We will be announcing the name in the coming days."
A Downing Street spokesman said the Prime Minister had sent his "very best wishes" to Mr Miliband and his partner. Mr Cameron wrote in a card: "Samantha and I would like to send you both our heartfelt congratulations on the birth of your baby boy.This is wonderful news and we could not be more pleased for you and your family."
Mr Miliband will take now take two weeks of paternity leave from Parliament, with his duties being covered by Labour deputy leader Harriet Harman.
The 40-year-old is expected to ensure he is named on this child's birth certificate, after admitting he was "embarrassed" to have forgotten to register on 18-month-old Daniel's records.
Mr Miliband has said he and barrister Ms Thornton, also 40, will "get around to" marrying "at some point".
