Robbie Williams and Ayda Field have welcomed their fourth child together, after he was born via surrogate mother

In an Instagram post, Ayda wrote: "Spot the difference...' On this Valentine's Day, we would like to celebrate love in the most awesome way... Beau Benedict Enthoven Williams.

"As with Coco, he is biologically ours, but born via our same incredible surrogate.

"We are so blessed to have our healthy son safely in our arms and are officially complete as a family. #happyvalentinesday #surprise #familyof6 #whodathunkitinthe90s The Williams Family xx. (sic)”

The happy couple also have daughter Teddy, seven, and son Charlton, five, together.

Meanwhile, when Coco - whose full name is Colette - was born, Ayda took to social media to explain the “difficult path” that led them to choosing a surrogate mother to continue having children.

She wrote at the time: "I spy with my little eye an extra little hand. So we have been keeping a very special secret!

"We are delighted to share with you that we have had a baby girl…. welcome to the world Colette (Coco) Josephine Williams!!

"It has been a very long and difficult path to get here, which is why we have kept it on the down low.

"Family comes in all forms, and this little lady, who is biologically ours, was carried by an incredible surrogate mother, to whom we will be eternally grateful. (sic)”

Robbie, 46, previously spoke about fatherhood as he said the new job had changed him after a life of “strippers and cocaine”.

He said: "Back in the 90s, it used to be strippers and cocaine and now it's hummus and celery and my life is much better for that.

"I used to live on rock star hours, which was go to bed at three or four o'clock in the morning, and wake up in the afternoon.

"You quickly realise when you have a child you are not an insomniac but a bit lazy and prone to exaggeration.”