Until 1982, when Mark Wahlberg turned 11 and his parents split up, there were 12 of them in the flat he grew up in; eight siblings, two parents, a grandmother and him. He was the baby.

Both space and money were tight; they shared the top floor of 25 Peverell Street, a Dorchester triple-decker, Boston’s word for three apartments stacked on top of each other. Mum Alma cooked for everyone, with Donald, dad, on the grill. Grandma watched. Sometimes they’d send the kids out for extras, like “government cheese”, which came orange and in squares.

“No matter what, my parents would basically kick us out at the crack of dawn and then tell us to be home at dinner time,” says Wahlberg now, “when we’d all get together and we’d all eat. Even if they were just throwing stuff together, leftovers, my parents would always try to make it special, you know?”

Wahlberg’s mother, Alma, will tell you that back then, ‘English muffin pizza’ was a family treat. It hasn’t made the menu of the 31st Wahlburgers, the latest sit-down burger restaurant from brothers Mark, Donnie and chef Paul, which opens in Covent Garden on May 20.

The government cheese remains, though, and the hungry can gorge on a Triple Decker of three burgers piled perilously between a bun. The family have given their history to the business: elsewhere is Mom’s Sloppy Joe and Alma’s Macaroni Salad. On the walls are the pictures of the boys growing up, as well as them grown; Donnie as the star of New Kids on the Block, Mark in Ted and Lone Survivor. Above the staircase that cuts down the middle of the restaurant is a black tile covered in the names of films and songs.

BEST BUNS IN THE BUSINESS: MARK WAHLBURG RUNS THE GROUP WITH BROTHERS DONNIE AND PAUL
ADRIAN LOURIE

The new site is the first venture for the chain outside North America. It is months late, the result of choosing a Grade One listed building attached to the Opera House. “Grade One listed means that everything we do, internally, externally, has to be approved not just by planning permission but by heritage as well” says Pete Warden, the Hospitality Director of LXA, who’ve project managed the move here, “right down to the fixtures we use for all the signs.”

They’ve made it through final inspections, though, and despite plating up fish n’ chips – a London exclusive – the site will be a carbon copy of its American siblings. The formula has worked so far and confidence is high: Covent Garden will seat 200 and is forecasting sales of 14,000 burgers in the first week; 115 staff have been brought on board to make it all happen.

“At one point, we were the fastest growing restaurant in the history of franchises,” claims Wahlberg, which is probably wishful thinking. Though the brothers previously had a successful restaurant called Alma Nove, Wahlberg admits the punny name “poured rocket fuel” on their growth. He wasn’t keen to begin with.

Even if they were just throwing stuff together, leftovers, my parents would always try to make it special

MARK WAHLBERG

“Paul didn’t mention it as a joke, but I wasn’t taking him seriously.

“He said he wanted to do a burger concept and I said ‘fine’, and then he mentioned the name Wahlburgers, and I said ‘absolutely not’. I just felt like I’d spent too many years building my own brand.”

Realising he could build something else, “something to pass onto the future generations” swayed things. Now the original gag is stretched thin; they’ve Wahlbowls (deconstructed burgers served as salads), their signature Wahl Sauce (something like ketchup, mayonnaise and hot sauce) and, perhaps best of all, Wahlbrewski, a pale ale from Boston’s Harpoon Brewery.

His connections must have helped, too. At last week’s VIP preview, a hastily put together crowd included Liam Payne, Octavia Spencer and Harry Kane; “David Beckham really wanted to come, but he was headed to China. He’s going bring his boys in when he gets back,” he says, “but the dream would have to be [Prince] Harry – he’ll have to bring in little Archie when he’s old enough.”

Mark Wahlberg’s Wahlburgers, in pictures

For a man who’s filming schedule went viral for its overwhelming strangeness – a 2.30am wake up, golf at 7.30am, a 9.30am round in a cryochamber – it’s astonishing he’s found the time to build a restaurant empire in between the hours on the green and, well, starring in blockbusters.

He insists the Instagram story detailing of his day-to-day wasn’t usual – “just for a movie called Wonderland, five months of agony” – but when setting the record straight he admits he “still prefers to get up early, work out, have my prayer time and all that stuff, do my reading and writing, play golf and have some additional exercise by the time the family’s getting up.” He won’t be drawn on exact time, but indicates a 5am rise would be a little late.

His brothers have been crucial to it all. “Donnie’s kind of the people person, dealing with marketing, stuff like that,” says Wahlberg, “but I run the business and Paul does the menu.”

This may be understating it, a bit: by all accounts, Paul is very definitely hands-on in most aspects.

“Everything has to be done down to the letter when it comes to the menus,” says Covent Garden’s head chef, Mark Inman, who underwent seven weeks training out in Boston for the role. “Paul is very much a stickler. He’ll come in, and he’ll taste this, taste that, taste everything.”

There’s a fair bit to taste; there are salads and sandwiches alongside the 10 types of burger, which include a vegan offering from Moving Mountains.

Does self-confessed ‘health nut’ Wahlberg actually eat his own product? “Of course! My favourite’s the Thanksgiving burger, the turkey one. But I’ll usually order like four of five burgers and have half or at least of a quarter of each one.” Why? “Because I love the taste of all of them.”

For now, that’s all, though there are plans for a breakfast menu soon, once they’ve a handle on the rest of it.

While Wahlberg is unlikely to be swinging by the restaurant any time in the immediate future, he and his brothers, and mum Alma, can chat to the restaurant at any time over a video link that’s hooked up to their phones. They say it’s not uncommon in the States, especially with birthdays and big groups.

It is a gimmick, but the family connection to the restaurant seems genuine. Wahlberg points to the 10-season television show that’s followed the restaurants since they launched: “My mum had a fun time doing it. You know, after my sister passed [in 2003, on the same day Wahlberg’s daughter was born], my mum was in a bit of a rut and so I think, that between the restaurants and her being able to be a hostess, and work on the show, it kind of gave her a sense of purpose again.”

The chain has purpose in spades. Other London sites are planned, before expansion across London and through Europe, too. They won’t be drawn on how many they’re gunning for, but however it tallies up, the family is a long way from 12 of them to a flat.

Wahlburgers will open on May 20 at 8-9 James Street, Covent Garden, WC2E 8BH, wahlburgers.com