The proud new daddy held tightly to the car seat carrying his precious cargo as the pair left New York's Lenox Hill Hospital. Eric Phillip arrived on Valentine's Day, and sharing the first pictures of the little boy Simon tweeted: "I never knew how much love and pride I would feel."
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Lauren – dressed in black –looked radiant three days after giving birth, her hair falling in waves around her face.
The 37-year-old smiled as she walked beside Simon, and little Eric slept soundly in his car seat as he faced the paparazzi for the first time.
TV's former Mr Nasty was full of joy and emotion at the birth of his son – posting three adorable snaps two days after his birth.
"Now you can see how very handsome little Eric is," he wrote with one of the black-and-white photos.
On Valentine's Day he let his Twitter followers know the little boy had arrived safe and sound, writing: "Very happy to say Eric was born at 17.45pm. Healthy and handsome."
He later explained his choice of moniker: "Named after my dad," referring to his late father Eric Selig Phillip Cowell, who died of a heart attack in 1999 at the age of 81.
The latest update was posted shortly after Simon left hospital with his new little family: "The last three days have been incredible. Eric, lauren (dogs) sqiddly and diddly all happy."
Lauren was admitted to Lenox Hill Hospital in New York on Friday after she went into an early labour. Simon jetted out of the UK to be by her side as she delivered their baby boy, who weighed 6lb 7oz and was born at 5.45pm.