"We're going to go out the front, are we?" Jamie Oliver says. "Righty-o then. This'll be interesting."

It's lunchtime in Sydney at Jamie's Italian and the restaurant is closed to prepare for a relaunch party that evening. I'm here for a photoshoot interview and the photographer has suggested we take advantage of the afternoon light.

"You can stay inside," she says. "I just want you closer to the entrance."

Oliver stands facing Pitt Street for his photo and the footpath froths into a flurry of pointing and waving and phone camera snapping. It's him! It's Jamie! The most famous chef in the world!

The chef smiles and waves at the sea of smartphones and craning necks. "This is excellent," says a public relations person near me. "Really great for buzz."

Oliver is Down Under for a week to relaunch the Australian outposts of Jamie's Italian, the family-friendly restaurant chain that arrived on our shores in 2011. The first Jamie's Italian opened in Oxford, England, in 2008 and there are now more than 60 worldwide. The chef's restaurant group has bought back all six Jamie's Italians in Australia after the previous co-owners and operators – hospitality company Keystone Group – went into receivership. Or "down the shitter", as Oliver puts it.

The British chef's best Australian mates and old restaurant partners, chef Tobie Puttock and wine bloke at large Matt Skinner, have rejoined Oliver, Puttock to consult and collaborate on the Jamie's Italian menus, Skinner to oversee the booze.

"That it's now fully owned by us means we can be even more dynamic," he says. "And, backed by Tobie and Matt, it sort of feels like we've got the old band back together."

"A restaurant's biggest strength is the people, and its biggest weakness is the people," Oliver says. "Because the boys are like family, they can provide an objective view on how to run things. They've also been busy doing freelance work and consultancy for other businesses, which is a talent in itself."

Happy days

Puttock and Skinner found fame in the early 2000s when, with Oliver, they co-founded Fifteen, the not-for-profit restaurant providing intensive training for unemployed and disadvantaged youth. The London and Melbourne Fifteen openings were documented in the Jamie's Kitchen TV series. Today, the trio are sitting around a table and conversation turns to the old days when Oliver and Puttock were on the pans at River Cafe – the landmark London restaurant where they first met.

"When I started working at River Cafe, I'd just come from doing loads of fresh pasta work in Italy," Puttock says. "I sort of strutted in there like 'I've been cooking in Italy all this time. I know what I'm doing,' and Rose [Gray, the River Cafe's late owner-chef] was like 'Yeah? Well, we don't give a f--- about what you've been doing'."

"Rose would eat Michelin-starred chefs for breakfast," Oliver says, laughing.

Puttock and Oliver remained best mates after Oliver's shaggy blond mane was noticed by a BBC talent spotter in the 1997 documentary Christmas at the River Cafe. His first series, The Naked Chef, premiered a year later and Oliver quickly became something of a hoodie-wearing herald for a new age of popular eating that saw us getting giddy about windowsill planter boxes and exotic ingredients like porcini and bocconcini.

It was Puttock who introduced Oliver to Skinner and over several boozy dinners, the idea of Fifteen was born.

"At first, Jamie was like 'It's going to be 15 seats with me and Tobie on the pans and Matt, you can do wine and front of house'," Skinner says.

"It was supposed to be like a little corner shop with a couple of students working for us. But, like most of Jamie's ideas, it started out small and morphed into something massive.

"A few months later, he's back in the country and says, 'Right, boys, we're doing it. I've got this old three-storey building and we'll do 120 seats. Plus, we're going to employ 15 students'."

"There's been nothing like it since," Oliver says. "Lots of cafes are doing something similar but nothing on that scale offering that level of intense training."

Fifteen launched in London in 2002 and is still going strong. The Melbourne branch opened to much publicity in 2006, but closed its doors in 2011.

Puttock points to several factors for the closure, including the high cost of running the foundation training chefs, plumbing issues in the heritage-listed building and a business partner who was "perhaps in it for the wrong reasons".

"Also, we didn't have ownership," Oliver says.

"I got back to the UK from launching it and realised that we had just opened something we had no control over. But, in a funny sort of way, I don't regret it. It was a beautiful restaurant and Tobes did a great job. The students who went through the program were properly looked after and never compromised.

"The mistakes we made were symptomatic of us being totally novices. We were really, really young. And if I look at my whole career, it's never been a straight line. It's zigzagged all over the field. But you get more battle-hardy and with this recent [Jamie's Italian] bump, instead of being a 5 per cent partner of an Australian group, now we're 100 per cent owners. That brings responsibility, but it also brings opportunity."

The power of predictability

Jamie Oliver Group is the commercial mothership of the chef's many and varied companies. It manages Oliver's cookbooks, television shows, licensing deals, magazine, website, cookery schools and 86 restaurants, including the Jamie's Italian and Fifteen brands, plus delis, pizzerias, London's Barbacoa steakhouses and the American dude-food-focused Diner.

The group's combined turnover in 2015 was £158 million ($278 million) and almost three-quarters of that was from Jamie's Italian restaurants.

"Jamie's Italian is middle Aussie, middle England," Oliver says. "It's not trying to be hipster. It's not trying to be cool. We want to be predictable – I think predictability is underrated."

For the first few months after Jamie's Italian opened in Sydney, the queue for a table could snake so far down Pitt Street that staff would supply salami for punters while they waited.

Although much of that buzz has faded, the restaurants were still a profitable part of the Keystone Group portfolio. It was debt Keystone acquired from expanding the number of bars and pubs under its ownership (venues such as Manly Wine and the Sugarmill Hotel in Kings Cross) that forced the company into receivership. Sydney's lockout laws were also factor in the group's collapse, said its directors at the time.

"The Aussie business was always a great business, just like in the UK." says Oliver.

"We always work with generally small, boutique operators that we know will get our culture. Keystone bought that company that we partnered with originally [Pacific Restaurant Group] and we never really thought, two steps removed, that certain things might happen. Then, of course, when it went down the shitter."

Oliver has employed something of a "business as usual, but better" approach to the relaunch of Jamie's Italian in Australia. Hence the employment of Puttock and Skinner to be his eyes, ears and tastebuds on the ground in Oz, and a new wine list and menu full of updated comfort food classics. Oliver says Jamie's Italian will serve half a million people a year in Australia and 7 million a year in Britain.

He uses only ethically sourced, sustainable ingredients and wants to prove that a business can serve quality produce with a clear conscience and still be successful.

"We need to show that doing good can be good business. With Jamie's Italian, I could get 8 per cent extra profit in two weeks, just by f---ing compromising everything. But I don't want to make my money that way.

"The future has to be about small businesses being energetic and excitable and medium-sized businesses becoming a lot more sustainable.

"Big businesses just need to be better."

Oliver, who has campaigned heavily for a sugary drinks tax in Britain, points to Coca-Cola as one of those big businesses that needs to be doing better.

"Not that they're my arch enemy – although they probably are – but, if you look at Coke and say, 'Could they be a health food company in 100 years?' I believe they can."

Sugar hit

In a response to calls from Oliver and public health experts, the British government announced the introduction of a sugary drinks tax in 2016. The tax is designed to help combat obesity by increasing the price of sugary soft drinks and using the revenue to fund primary school sport.

Oliver is concerned about Australia's public health and says our government also needs to introduce a sugary drinks tax.

"Australia is kind of up there with the most unhealthy countries in the world and it just doesn't feel right to me — it's not your place to be there," the chef says.

"I donated 18 months to telling the sugar tax story in the UK, but it's all based on science and fact and the same science and fact applies to Australia. The conservative UK government didn't want to make that sugar tax policy, but we got it because, when it comes to the crunch, a modern day prime minister has to act on the data if the story is told correctly.

"I think the interesting thing about Australia is that not one major party is even debating or sniffing about it. But France, Portugal, Hungary, Ireland and the UK are all in. Australia will fall in line, too."

Critics of a sugar tax in Australia claim the government shouldn't be interfering with our freedom of choice. Similar to what happened with the introduction of plain packaging tobacco laws and push for pokie reforms, the term "nanny state" is thrown around a lot.

"Australia is a bit obsessed by the nanny state thing, isn't it?" says the chef. "But ask Aussie parents if they're cool with 15 cents on a can of sugary soft drink going to schools for food education and sports. When we said that in the UK, the sugar tax polled at 75 per cent approval. The nanny state argument from knobheads is bollocks. This is f--king common sense."

To get a sugary drinks tax implemented in Australia means "mobilising Aussie parents to just tell the government what to do," says Oliver.

"When you give people clear information, they make good choices."

"The only way you're going to get a drop-off of anything bad is if it's an environmental change," he says. "So that's labelling, that's advertising, that's education, that's sugary drinks taxes. That's making good shit cheaper and horrible shit more expensive or harder to get.

"But the genius of the sugary drinks tax is that when it happened in the UK, it was the first time I can remember the government standing up and giving the industry a spank. Every other part of the food industry witnessed it so, at a rate faster than I can tell you, the whole industry is reformulating shit out of the food chain. Cutting back on all the salt, fat and sugar. They haven't been asked to do it either — it all comes from that one action."

Next gen

We finish the interview and the trio go back to talking about the early days of Fifteen. Puttock asks Oliver how former student Ralph Johnson is doing these days.

"Oh, Ralph? Ralph's doing awesome, man!" Oliver says, without missing a beat. It's the liveliest I've seen him all afternoon – even after all the swearing about the lack of a sugar tax in Australia and smiling to fans on the street. "He's coming back to the UK after a stint at the Spotted Pig in New York."

Oliver whips out his phone and starts bringing up the Instagram accounts of other former Fifteen students.

"Do you remember Gavin Gordon?" Oliver says to Skinner. "He's just opened this posh MCK Grill in Essex. And there you go – the word 'sustainability' at the top of the website.

"What we were being innovative about years ago, that's become standard practice now. I think I'm speaking on behalf of the three of us when I say we were the young talent back in the day, and now we're watching young talent come up.

"They're really clever, they're really well versed and they're super talented. The new generation of chef is f---ing phenomenal.

"I go into the kitchen with these young guys now and watch them cook and I'm like, 'I don't know how to do that.' You just sort of let them get on with it, you know."