And he’s off – taken up by the righteous enthusiasm that first turned him from the Naked Chef to a campaigner with the ear of prime ministers. “There’s really no place regularly for sugary sweetened drinks in the home,” he says. “I’m going to sound like such a bore but I’m going to say it anyway. Enjoy it in the cinema and on your holidays and at the fair – that’s the point of a treat. But you wouldn’t have candyfloss in your house on a shelf.
“I want you to have sugar because it makes you happy, but I want you to know when you’re having it. If you think about it, a Mars Bar has always been honest. It’s never lied to you and said it was something else. It’s the hidden sugar that’s the issue. And you won’t find any qualified practitioner in medical care that sees any place for sugary sweetened drinks in the home.
“I want you to eat cake,” he tells me earnestly, but he wants me, and indeed you, to “get it right most of the time”.
What about our kids? As a mum of a four-year-old I have a daily fight to keep the sugar at bay. “Nearly everything that could go great for your kid happens in the supermarket with you and your chequebook and the trolley,” he says. “It doesn’t happen at home, it happens in the supermarket. If you don’t buy rubbish, you won’t eat it.”
How does Jamie – father to Poppy, Daisy, Petal and Buddy (13, 12, six and nearly five) – handle sugar in his own home? “My missus Jools is an amazing mum and we have never brought sugary sweetened drinks into our house. There is absolutely no need. I probably would offer one up on a special occasion or on a beach, but my missus wouldn’t have it. She’s way stricter than me so that rules that one out.” If he gives Buddy some fruit juice it’s diluted. “It’s not empty calories but it has got sugars and citric acid so it’ll be the same as pop for bad teeth.”
But it’s not enough for parents to police the trolley in the supermarket aisles and for governments to impose taxes; everyone has to change their priorities, from the supermarkets to consumers. For Oliver this applies to healthy food choices in general, not just sugar.
“We need to make fresh food more affordable than processed food because the most at-risk people right now won’t be my kid or yours. They will be five-to-11-year-old deprived kids who are four times more likely to be overweight or obese than ours.”
Wasn’t he supposed to have fixed working-class nutrition ten years ago with School Dinners? He saddens a little. “I admit I haven’t succeeded, mainly because I haven’t single-mindedly gone for it. In Britain, eating well and feeding your kid right and being aware about food is all considered very posh and middle class, but the reality is that in most of Europe some of the best food comes from the poorest communities. Our harder-to-reach poorer communities are suffering more.”
The passion’s still there, then, but Oliver admits he’s increasingly aware of his age these days. He has started to look honestly at his own “engine” and reconsider some lifestyle choices: “Sleep has become profoundly important to me,” he explains. “I was never getting enough of it and I didn’t understand the value of it. And I treat it like work. Just like I do with little Buddy when I tell him to get to bed, I get to bed! I have little vibrating things that shake me when it’s 10pm.”