Sheffield Gave Soccer to the World. Now It Wants Credit.

As far as the man in the food truck is concerned, the patch of land he occupies in Sheffield, England, is about as humdrum as they come. To him, the spot — in the drab parking lot of a sprawling home improvement superstore, its facade plastered in lurid orange — is not exactly a place where history comes alive.

John Wilson, an academic at the University of Sheffield’s management school, looks at the same site and can barely contain his excitement. This, he said, is one of the places where the world’s most popular sport was born. He does not see a parking lot. He can see the history: the verdant grass, the sweating players, the cheering crowds.

His passion is sincere, absolute and shared by a small band of amateur historians and volunteer detectives devoted to restoring Sheffield — best known for steel, coal and as the setting for the film “The Full Monty” — to its rightful place as the undisputed birthplace of codified, organized, recognizable soccer.

For now, their attempts have mustered a walking tour of the city, conducted through a homemade app, and a few slightly weathered plaques. But Dr. Wilson and his compatriots have a bold vision of what their efforts might produce: a “digital museum” of Sheffield’s soccer history, a sculpture trail and — more than anything — a clear and prestigious identity for a city that has, in recent times, struggled just a little to define itself.

As they look to use the city’s past to shape its future, though, they do — Dr. Wilson warned — have a bit of a “tendency to go off on tangents.”

He is not wrong. In the half-hour walk to the parking lot, Dr. Wilson, 65, and two of his fellow enthusiasts, John Stocks, a 65-year-old retired English teacher and author, and John Clarke, a retired computer engineer who is 63, touched on a range of subjects that included — but was not limited to — social migration patterns in Victorian England, the Netflix series “The English Game” and the practice of topping walls with crozzle, a waste product from iron furnaces.

They discussed each digression with glee, eagerly diving every rabbit hole. Like many ardent hobbyists, they reveled in the detail as much as the sweep.

The picture they have in their minds, though, is clear.

“In the 1850s and 60s, there were hundreds of teams, playing each other in competitive games, on pitches all over the city,” Mr. Stocks said. In studying Sheffield’s soccer legacy, he said, the past they have unearthed reveals the city as “the home of the first real football culture anywhere in the world.” That, they believe, might also be the key to its future.

But the title “Home of Football” — always capitalized and, in flagrant disregard of New York Times style, never “soccer” — is a contested one.

It is semiofficially applied to Wembley, the stadium in the endless gray expanse of northwest London that is the headquarters of both the English national team and the Football Association, the game’s governing body in England.

Visit England, the country’s tourist board, backs another contender. It describes Manchester as the “Home of Football,” on the grounds that it hosts two heavyweights of the Premier League and the National Football Museum. Manchester is also where the Football League — the sport’s first professional competition — was formed.

In comparison, Sheffield’s candidacy for the title is distinctly homespun. There is a brief précis of the city’s role in the game’s formation on the website of its tourist board, and an archive is on display in the “local studies” section of the city’s library.

“We’ve not been very good at promoting ourselves,” said Richard Caborn, a former lawmaker from the city and the minister for sport under Tony Blair’s Labour government. “We’ve never really positioned ourselves to exploit it.”

Sheffield Home of Football, an educational charity established by Dr. Wilson and his fellow travelers, has stepped into that void.

“We’ve been through the history and we have the documentation,” Mr. Caborn said. “This isn’t a claim. It’s evidence-based.”

Sheffield’s case is compelling. Sheffield F.C., the world’s oldest club, was founded here. So, too, was Hallam F.C., the world’s second-oldest. Hallam’s home, Sandygate, has been hosting soccer since 1860, longer than anywhere else. It was in Sheffield, too, that the rules of the game that would become soccer were first written down.

Mr. Stocks and his fellow “obsessives” — his word — draw the greatest satisfaction in finding the supporting evidence. It is painstaking work, trawling through both digital and physical archives, but worth it, he said.

“There are some of us who will stay up all night chasing down a lead they’ve found,” he said. “I’m not quite as bad as that, but I do devote quite a lot of time to it. I have quite a few other projects I’m supposed to be getting on with, but the reality is that most of the time, I’m doing this.”

Because of their work, Sheffield can now, with a reasonable degree of confidence, claim to be home to the first derby match in world soccer — the meeting of city rivals Sheffield F.C. and Hallam on the site of the home improvement store’s parking lot — as well as the first corner kick, the first use of the crossbar and the first match report.

Mr. Stocks has also tracked down a suggestion that passing was invented in Sheffield — not in Scotland, as is widely believed. There are accounts of what sounds an awful lot like professionalism. “We think there’s a chance the first German team was founded here, too,” Dr. Wilson said.

Part of the thrill, they admit, is correcting some of the inaccuracies in what they call soccer’s “folk history.” Their driving force, though, is the sense that their discoveries can define not only what Sheffield was, but what it might yet be.

In the 1980s and 1990s, Sheffield was hit hard by the decline of Britain’s heavy industries; even harder than much of the rest of northern England, Dr. Wilson said.

Built on steel and coal, the city was run for years by a left-leaning council that was a gleeful thorn in the side of successive British governments. “They called it the Socialist Republic of South Yorkshire,” he said. As the factories and mines shuttered, Sheffield struggled both for investment and identity.

The various modern conceptions of Sheffield have not yielded a new one. The backdrop for the film “Brassed Off,” as well as “The Full Monty,” and home to Pulp and the Arctic Monkeys, two of the defining British bands of the last quarter-century, the city also developed a reputation for advanced manufacturing. It is where, every year, the world snooker championship is held.

Nothing, though, has ever quite settled. “The council are leaning into music quite heavily now,” Mr. Stocks said. “But it won’t stick. We’re not Liverpool. We’re not London. We’re not Glasgow.”

Soccer, though, is different. To him and the others, Sheffield’s role in shaping the most popular sport in the world should be its calling card, its claim to fame — not to attract tourists necessarily, but so it can find its place in the world, can define its sense of self.

“Most people here only have a vague awareness of some of it,” Dr. Wilson said. “They don’t know we have this unique identity, that this is something we gave to the world. No other city can say that.”