Conservative leader David Cameron has announced his new baby son is to be called Arthur Elwen.
Samantha and David Cameron with their new arrival
Mr Cameron's wife Samantha, 34, gave birth to their third child by Caesarean section on Valentine's Day.
The Tory leader said the names did not have any particular significance but he believed somebody on his father's side of his family was called Arthur.
"Arthur we've always liked as a name and Samantha found Elwen in a book. We thought it was a good name," he said.
Elwen is a name apparently of English origin which means "elf-wise friend".
Newspaper reports have previously suggested that Mr Cameron's supporters play a game in which they imagine themselves in a political version of Middle Earth, with their leader cast as the Tory version of Lord of the Rings' Frodo.
But a Tory spokeswoman stressed the couple had simply chosen the name from a book of baby names and it had nothing to do with Lord of the Rings.
Mr Cameron was at his wife's bedside when she gave birth to Arthur, who weighs 7lb 13oz and has black hair and blue eyes.
He said the family were doing fine, despite sleep deprivation.
"It's absolutely great to be home and it's actually been very easy," he told reporters.
"Arthur is doing really well. He is feeding nicely and doing all the right things. He was wide awake before we came out [before the cameras] and then he suddenly decided to shut his eyes."
The Camerons, who have been married since 1996, have two other children, Ivan, three, and Nancy, two.
Mr Cameron said the older children were getting used to their new brother.
"They seem very chuffed about everything and it's lovely. I have had better nights sleep but that's all part of it," he said.
Parliament has just begun a week's break but Mr Cameron defended his decision to take two weeks' paternity leave.
He said: "I'm not taking two weeks off, I've probably signed about 100 letters already this morning. I'm still working and my constituents will still have a full service."
The family are planning to go to their house in Mr Cameron's Witney constituency later on Friday.