meets Oliver, he is animated, speaking at length about his new school food challenge, his love for teachers, what politicians should do next and how the idea of turning 40 has re-energised him. He's been up since 4.30am.
A decade ago, cameras followed Oliver as he strode into Kidbrooke School in Greenwich (now Corelli College) and banned chips, provoking a furious reaction from students and staff. He was seen as out of touch, more at home in a posh restaurant than a mass catering venture.
But his expletive-filled rants about processed meat (the DVD came with a swearing-free option) and his passionate advocacy of courgettes and home-baked bread won over the British public, the government and, eventually, the teenagers of South London.
"I've been thrashed and kissed and beaten by my many experiences [with] different governments and different aspects of food education," he says. We are at his film studio in Shoreditch, East London; its 1950s-style tiling, vintage cabinets and non-matching chairs will be familiar to anyone who has watched his Food Tube channel on YouTube.
It was Oliver who brought to the country's attention the fact that schools were being expected to feed children on just 37p a day. His Feed Me Better petition - which called for the budget to be at least 50p per head - gathered 271,000 signatures and led Tony Blair's Labour government to dedicate pound;280 million in funding to the cause.
Now Oliver is back with another petition, this time demanding that food education is made compulsory across the G20 group of the world's wealthiest nations.
Over the past 10 years, Oliver's crusade has achieved a great deal. Food education is on the national curriculum in England; new food standards governing school dinners have been put in place; and all infants in England now receive free school meals. But as fast as healthy eating has been moving up the political agenda, obesity levels have been rising, too.
In 1980, fewer than one in 10 people were obese in the developed countries that make up the Organisation for Economic Cooperation and Development; now 18 per cent of the adult population are obese.
To combat the problem, governments around the world are enacting tough legislation. A tax on sugary drinks in Mexico, which has the highest obesity levels in the world, has lowered consumption. France has brought in a similar measure.
Oliver predicts that the UK will do the same, whichever party is in power. "No one likes tax but it's going to happen," he says. "It can lower the amount of consumption, which if you look at tobacco is no bad thing, and it can raise funds.
"It's the lowest hanging fruit for new money and you know they need money. There's a billion quid to be raised through a 20 per cent sugar tax, and I would give half of it to the NHS and I'd give half of it to schools.
"These companies would still be profitable. Let's get good money going to good places and invest in good people correctly. There are a million lawyers that are way cleverer than me and slicker than me who will build a brilliant case against it, but how about `You're all talking bollocks' because the only thing that's important is making this stuff harder to get and these people [in schools and hospitals] funded better."
Yes, he does sell cola in his restaurants. But, he points out, it's nice as a treat.
Oliver has always gone with his gut instinct. When he began Jamie's School Dinners, he knew that the academic side of proving the links between diet and health - measuring, collecting and analysing data - would be expensive, complicated and never-ending. So, instead, he simply asked teachers what they thought about the issue.
"They're the ones dealing with the kids every day, and when we changed the food it was quite extraordinary, it really was," he says.
A `whippersnapper' no longer
Now, though, Oliver is tackling the science. He has taken a diploma in nutrition with St Mary's University in Twickenham, and is planning to go on and get a degree.
His struggles with dyslexia are well-known. Although he runs a multimillion-pound business empire and is happy meeting heads of state, it has taken some courage for him to return to studying after leaving school at 16 with just two GCSEs.
"I absolutely loved [the diploma]," Oliver says. "It's unusual for me because I did really badly at school, so I think you're always left with that hangover even when you're 39 years old.But I just loved it."
And at the end of this month, he turns 40. He is the enfant pukka of cookery no longer. "I've always been the young whippersnapper boy on the scooter, twizzling down the stairs, and I'm not that any more," he says, laughing.
"But I'm looking forward to the next 10 years. Ten years ago it felt like I was pushing a rock up a hill. It doesn't feel like that any more; it feels like we're pushing a rock down a hill."
Join the food revolution
This year's Food Revolution Day takes place on 15 May. The event was created as part of Jamie Oliver's campaign to put practical food education on the school curriculum.
"It's essential that we arm future generations with the life skills they urgently need in order to lead healthier, happier, more productive lives," he says. "I passionately believe that this is every child's human right."
To mark the first Food Revolution Day in 2014, TES broadcast a live cookery lesson that pupils across the country took part in (watch the lesson at bit.lyLiveCookingLesson).
Oliver's petition to urge G20 countries to make food education compulsory has been signed by more than 750,000 supporters.
To find out more about this year's Food Revolution Day, and to sign the petition, go to foodrevolutionday.com