The first thing I do when sitting down for lunch with Robin Rowland, the boss of Yo! Sushi, is look under the table for his Wellington boots. For, while the Japanese-style restaurants seem the epitome of urban cool, the man behind them is a recently converted country boy, through and through.
His friends warned me how he's known to turn up for dinners at the poshest restaurants with his wellies in a bag.
"They told you that, did they?" he chuckles. "I guess it might seem a bit eccentric, but I moved from London to a farm in Surrey and it gets terribly muddy outside my house. Wellies are very useful things to have on you."
We meet in the Yo! next to St Paul's cathedral, about as central London as it gets, and Mr Rowland is in full townie garb, no mud-spattered footwear in sight, having left his boots at the office.
He doesn't give interviews much, but with a business that's expanded faster than practically any other chain in the country during the last few recession-bound years, he deserves to tell his story.
From his arrival to take over the operations side of founder Simon Woodroffe's handful of London bars 12 years ago, he has built up a 60-strong chain across the country and is now taking his conveyor belts global.
"Conveyor belts?" The uninitiated might ask. Conveyor belts. That's what Yo! is all about.
Perhaps I should explain. Yo!'s punters sit on stools around a large bar containing a mini conveyor belt, which transports a constant stream of small, neatly presented sushi dishes on a circuit around a group of chefs who work in the middle. The customer simply picks out the plate they want as it travels past them.
It's fun, but also makes good business sense. As a rival says: "The beauty is, you can drop it in almost anywhere – a shopping mall, an airport lounge. You just cordon off an area, put in the belt and some chefs and off you go."
Despite it being a sunny Monday (like vampires, restaurateurs hate sunshine – it tempts customers away to parks and pub gardens), the Yo! at St Paul's is doing a busy trade.
As I arrive, half-a-dozen Japanese gents rock up and occupy one side of the conveyor, tucking into miso soup and nigiri rice parcels. I'm convinced Mr Rowland has bussed them in for The Independent's photographer, although he pleads his innocence.
Mostly, though, it's office workers and tourists, cutting in for a fill-up before heading back into the spring afternoon.
The conveyor belt means you escape the embarrassment of having to order – and the accompanying hazards of not knowing your sashimi from your gunkan. You just grab what looks tasty.
And tasty it is, without being the carb-and-fat-fest of so many chain restaurants. Mr Rowland says that's part of what attracted him to the business.
"It's healthy – and back in 1999 when I was looking at what I wanted to do next, I recognised that would be a big growth area, especially with the rising spending power of women."
Mr Rowland himself, at 50, is a good ad for it. Slim, energetic to the extent of fidgetiness, he's constantly reaching into his bag for spreadsheets, gesticulating and reaching to the belt for dishes for me to try. A father of three, he skis, sails and plays tennis.
Facially, he's a ringer for a younger Jeremy Paxman, or Jonathan Miller – perhaps it's the Roman nose and the longish grey hair – or is it the "academic air" his friends describe about him?
As James Horler, currently running the Rocket and Ego restaurant chains, kidded: "Quite intellectual, is our Robin – that's why he doesn't get his hair cut properly."
After St Dunstan's college in London, he studied politics and American history at the University of Kent and the University of South Carolina.
"The Deep South was a weird place then, they were still fighting the Civil War down there – I'm sure my classmates' fathers had conical hats at home in the cupboard."
Weird it may have been, but it triggered something of a love affair with the US, which brings me to why I'm here. Mr Rowland is, after 10 years of research, pushing Yo! into the potential goldmine – or potential bottomless pit – of the US.
He has opted for Washington DC as his launchpad. Union Station will be the first, in June, followed by three more in the DC area.
"The great thing about that place is that we'll get fantastic word of mouth very quickly – traffic between Union Station and New York is just phenomenal. After that, we'll look for shopping centres, triple-A, prime downtown locations."
But isn't he worried about the failures of so many Brits attempting to crack the States – Marks & Spencer and Tesco, to name but two? Not a bit of it. He reckons his slowly-slowly approach will pay dividends for his backers at the French private equity house Quilvest.
"What we think we've got right is a team that is all-American. Run by Americans, for Americans – people who understand the food and the culture.
"The market is there and waiting for us. There are no real rivals to Yo! in the US – the only sushi bars are still Mom and Pop operators, so the opportunity is tremendous."
He chose the fledgling Yo! after a career at Whitbread, Grand Met, Scottish & Newcastle and what's now known as the Restaurant Group. All big companies. His boss at TRG at the time, Andrew Guy, recalls: "He was quite corporate when he joined us, but we always gave a lot of independence to our managers and he really loved that, so he wanted to do something more entrepreneurial when he left us."
But why choose Yo! Sushi?
"It just seemed right. It had that 'food of the future' feel to it," Mr Rowland says. "I've always liked my tech – and this just seemed brilliant to me," he says, waving his chopsticks towards the conveyor belt.
Visitors to the first Yo!s will remember the robot waiters which travelled through the restaurant serving drinks and food. Sadly they are no more, but Mr Rowland does not rule out bringing them back.
"They were brilliant, weren't they? We set them up so that during the day and early evening they'd say: 'Please move out of the way' when customers were blocking their path. But after 9pm, they'd change to 'Would you move your fat ass?' Very funny. Trouble was, they cost as much as a small car."
He added: "You have to keep up with technology. You have to keep in touch with what young people are up to. Take social media – it's so important. The companies that are using it now to good effect are the ones that will thrive in the future."
A couple of weeks before we meet, Mr Rowland ran a "flashmob" experiment at his restaurant in Soho. "We Tweeted: '97p a plate'. A while later, as I was heading out of town, I got a call from the restaurant: 'Er... you've got to get down here and see this is for real.' There were literally three-hour queues around the block."
The internet, robots and healthy food. A modern recipe for success.