Why Sunday? Kidman's father reveals all

As the news broke yesterday that Nicole Kidman had given birth to a baby girl, the main point of speculation was not what whether she looked like her mum or her dad - musician Keith Urban.

Nor was the talk of how great a bidding war the first pictures of the baby would spark - the couple have reportedly turned down all media offers.

What everyone really wanted to know was why Kidman and Urban named their firstborn Sunday Rose.

She came into the world on Monday US time. It was Tuesday in Australia.

Speculation in the media pointed to Australia's Queensland island chain The Whitsundays - where Kidman celebrated her 40th birthday, and a name expert suggested the moniker may have come from an African tradition, whereby tribes name their daughters Sunday.

The truth, according to Kidman's father Dr Antony Kidman, is much simpler.

It's an homage to Australian arts patron Sunday Reed, according to Dr Kidman.

"I have read a bit about Sunday Reed and her husband John - she was a key mover and shaker in the arts around the beginning of the century," he told Australia's Daily Telegraph.

"The name Sunday struck me as being a nice name for a woman, so my wife and I mentioned it."

Sunday Reed and her husband had a menage-a-trois type affair with Australian artist Sidney Nolan for nine years during the 1930s. As a result of the affair, Reed became Nolan's muse.

In January Kidman and Urban visited the Art Gallery of New South Wales, where a retrospective exhibition of Nolan's works was displayed.

Photos of the couple leaving the gallery, with Urban's hand in front of Kidman's belly, heightened pregnancy rumours.

Shortly afterwards the pair announced they were expecting a baby.

Urban's brother Shane told the Sunshine Coast Daily Rose was his grandmother's name.