Josh Hartnett and Tamsin Egerton welcome baby

Josh Hartnett and Tamsin Egerton have welcomed their first child into the world.

The 'Black Hawk Down' actor and his 27-year-old partner - who have been dating since 2012 - were seen leaving St. Mary's Hospital in London yesterday (01.12.15), with the proud father carrying the new arrival in a car seat.

The couple have not yet confirmed whether they had a boy or a girl, or any other details about the baby's birth.

The pair - who first met on the set of 'The Lovers' in 2011 - confirmed in July they were expecting a baby.

Their representative said at the time: "It's true and they are beyond thrilled."

Josh - who previously dated actresses Kirsten Dunst, Scarlett Johansson and Amanda Seyfried - recently spoke about his desire to have children.

He said: "I have to get a car that's safe for my kid. I don't have a kid yet, but that's the idea coming into my head these days."

And the 'Penny Dreadful' actor also admitted some of his on-set romances were "mistakes".

He said: "I've met very important people in my life doing films. Sometimes that had consequences that were just awful for everybody involved. Some were fantastic all the way through. Everybody makes mistakes dating people they work with."