When John Pettman was 16 he had two part-time jobs while he studied at college. One was stacking the shelves in his local Tesco, the other working for the Royal family.

Regularly called upon to help the team of butlers at Buckingham Palace and Sandringham, he’d catch the train from his home town of Dover and within hours of leaving the Kent countryside behind him, would be up close and personal with the Windsors.

In fact, if ever you pondered whether Queen Elizabeth II really did keep marmalade sandwiches in her handbag, as her Platinum Jubilee skit with Paddington joked, he may have the answer.

“On my first day at Sandringham,” the now 43-year-old recalls, “the Queen came up to me while I was doing the washing up in the pantry.

“She had a jar of marmalade which she needed opening.

“I was this spotty 16-year-old in uniform and she came up to me, knew my name and spoke to me for several minutes, just the two of us.

“She asked where I was from, what my parents did; she was absolutely lovely. She thanked me for helping out because they were short-staffed at the time.

“I was working there over my 17th birthday in February 1998, and I was up close and personal with them – serving breakfast, lunch and dinner every day.

“I even walked the corgis.”

He got a remarkable insight into one of the world’s most famous families and a career in household service which has seen him travel the world, brush shoulders with global superstars and develop a career as far removed as the those depicted in the likes of Downtown Abbey it is possible to imagine.

Just don’t expect him to spill the beans on anything he saw there – or anywhere else he’s worked.

“Discretion,” he says, “is extremely important to me and those I have worked with.”

I squeeze out of him the fact he’s worked for billionaires and once chauffeured the late great Tina Turner around Cambridge while working for a family. Everyone else, however, he’s pretty coy about.

“I’ve met some amazing people,” he says, “but I don’t talk about it openly.”

Today he runs a number of specialist companies all focused on recruiting butlers, chauffeurs, house-keepers, chefs and estate managers to the world of the high net-worth individual.

His main business is Exclusive Household Staff, based in London, which employs more than 20 staff and has some 3,500 clients and 35,000 workers on its books.

Business, he says, is booming globally. But not so much in Kent – aside from some of the plusher areas to the west of the county.

Opened to be within walking distance of his home is the Exclusive Butler School in Herne Bay. It offers a two-week crash course in the art of working in “high-end households”. Facets of the course include specialists teaching floristry, mixology (so you can blend the perfect cocktail) and cigar etiquette.

He’s also got a recruitment agency for nannies and recently launched Luxury Yacht Interior Training.

“We train people working on superyachts,” the father-of-four explains. “We have a contract with a billionaire family where we basically train all their staff across their fleet of yachts. It’s about 300 people across seven boats. The idea is we create a standard across all of them.”

I blunder at some point and refer to the roles as being servants (“not a term I like to use,” he gently admonishes), and it’s one I completely take back when I realise how much money is at stake if you decide to opt for a career in such service.

“For a butler emerging from one of our training courses,” he explains, “they’d be looking at a starting salary of between £25-30,000. But that’s entry level and often will include accommodation.

“But the more experience you get the more you can earn. The top-level butlers are on £120,000. If you move into household management, then there are chiefs of staff out there on £300-400,000 and I’m not exaggerating.

“The average wage for butlers is probably around £50-60,000 a year. It’s bloody good money.”

Certainly better than local journalism, I can comfortably vouch.

Housekeepers, he adds, can earn £45-50,000 while nannies can earn “mega money”.

And he speaks from experience.

John had got his summons to the palace after enrolling at Thanet College (today Broadstairs College). Training to be a chef, he’d embraced front-of-house duties too. So when his lecturer, a semi-retired page at Buckingham Palace, was called up by his former employers to assist during a big event he took two of his best students with him.

For the remainder of his college career, the young student would frequently be called upon to help out with state visits or royal occasions. A more regal work experience opportunity it’s hard to imagine.

He was there when the Emperor of Japan visited, as well as helping out during the then-Prince Charles’ 50th birthday bash.

But when he reached 18 he opted to broaden his experience. Another former Thanet student – Ben Newick – had been head butler at the British Embassy in Paris since joining in 1984.

John explained: “He always used to take students from the college once they had finished their studies.

“So I left home and moved there. There was a head butler and effectively three footmen and I was one of those; an under-butler.”

But unlike the specialisms of staff at Buckingham Palace, the Paris role allowed him to get involved in a host of different jobs.

“At the palace,” he explains, “you’re one of 100 people. You’ve got people looking after the wine, someone else the silver, another the glass and crystal. In Paris we did it all.

“I did four years there and it took me into the world of private service.”

His next job? Working for a Swiss billionaire. “I managed a 28-bedroom manor house on 1,200 acres of land and I was 22. I had a four-bedroom house in which to live, a high salary, and was running the show because I had six years of the highest level of private service behind me.”

He went on to be a chief of staff for another family before, for the last 16 years, acting as the middle-man matching qualified staff with private families and wealthy individuals worldwide.

But he’s never forgotten the start he got at college in Broadstairs.

In a tie-up with the college today, his company runs the Exclusive Butler Academy.

“I wanted to give back,” John explains. “I wanted to give people a start like I had because not everyone can start at Buckingham Palace or work at the British Embassy.

“We go in once a week. It’s a non-profit partnership where we work with the students.

“Then, each year, the top students will get asked to interview with me and if successful will secure a scholarship worth £7,500 which gets them through our two-week butler training course. They get the qualification, the uniform and then we put them onto the books of Exclusive Household Staff and we help find them work in the industry.”

There’s also a chance to see the next generation of butlers in action.

Three times a year an Exclusive Royal Butler dinner service is held at The Yarrow – the hotel owned and operated by the college which sits on the edge of its campus.

“We try and create the feeling you would get if you turned up at Buckingham Palace to be a guest of the King or Queen.

“It’s all butler service, so there’s no choosing off a menu. If you were invited to the palace you don’t get to go in and say what you’d like. You go in and you eat what you’re given.

The British butler is still the gold standard

“Obviously dietary requirements are clarified beforehand, but once you’re sat down everything will be served at the same time. It gives our team and the students the chance to experience high-end service.”

The next date at The Yarrow is in February (£60 per head if you’re interested).

And in case you’re pondering following in his footsteps? The good news is being British is a great advantage globally.

“Everyone thinks of the British butler,” explains John, “and we’re still held in high regard globally. It’s still the gold standard.”