Beaming with delight, Labour leader Ed Miliband and his partner Justine Thornton present the newest addition to their household.
Baby Samuel Stewart Thornton Miliband arrived late on Sunday night.
Dressed in a babygro that's still too big for him, Samuel slept contentedly through his first photocall.
Proud mum Justine, who earned favourable comments with her chic maternity style, looked to have fully recovered from the birth.
On announcing the news, the politician said he was "over the moon".
Their newborn is a brother for their eldest Daniel.
Like Prime Minister David Cameron, who took paternity leave, Mr Miliband will take two weeks off to care for his son.
At Prime Minister's Questions, Deputy Prime Minister Nick Clegg offered the couple, both 40, his congratulations.