Oliver and his wife Jools have confirmed the name of the latest member of their brood, a boy called River Rocket.

Jools hinted at the name on Instagram this week with a cryptic post of a poster emblazoned with an inspirational slogan of Lorna Jane proportions – "Dream Big River" – along with the rocket and blue heart emoji.

The name River has sentimental value for the food artist formerly known as The Naked Chef. The River Cafe was where he was discovered by the BBC in 1997 while working as a sous chef at the upmarket eatery.

A day after his cameo in the documentary Christmas at the River Cafe, five production companies offered him his own show and within two years he was a household name. In 2000, Oliver married Jools and now the couple are the proud parents of five children, including Poppy Honey, 14, Daisy Boo, 12, Petal Blossom Rainbow, six, and five-year-old Buddy Bear Maurice.

Oliver confirmed the news on Instagram overnight, officially introducing the baby, who was born on August 8, to his fans with a family photo.

"So the littlest one is stared out and sleeping again ... it's probably polite to formally introduce the new boy to you, his names River Rocket Oliver we think it suits him and he's a little gift and we are all very happy ... Thanks for all your kind wishes big love jamie and gang X X X."

Jools, a former model turned childrens wear designer, has previously spoken about how the couple go about naming their children.

"They all have more than one name because I couldn't decide. I'm not sure where Petal Rainbow came from – apparently it's a My Little Pony! I wanted to call her Rainbow but Jamie told me to calm down," she told Gurgle magazine.

"With Buddy it was quite fun choosing a boy's name, as I hadn't done it before. And I hate people's opinions on names. Whatever you call your baby is your decision."

Baby Oliver No. 5 shares the same name as two of Australia's most high-profile children. Model Megan Gale's son River, and Rocket Zot, son of Sam and Lara Worthington.