Turns out you can make a pretty good guess about someone’s age, and the cultural circumstances of their youth, based on what they think of Dr. Martens.

Dr. Martens boots and shoes have been adopted by group after group in the 74 years since they were first sold commercially in Germany. In their first decade, most sales were to housewives. Then came the factory workers, followed by post office employees, then hippies, rock and rollers, and, later, glam musicians. Also around then, there were the skinheads and punks, the New Wavers and goths, the grunge crowd and yuppies. Today, you’re likely to see those thick rubber soles on the feet of teen influencers and fashionistas. It’s little wonder new investors have been piling into the shares over the past three months.

In any case, it’s anyone’s guess which consumer groups will come next.

There are no neat lines between each new phase of customer. There are anecdotes about skinhead gangs in North London being chased through alleyways by police in the late 1970s, and everybody involved was wearing DMs. In some places, multiple generations of families all own a pair of Docs.

“The shoe design isn’t trendy: The bestselling models are black patent leather with thick rubber soles,” Michael Beverland, author of Building Brand Authenticity, which uses Doc Martens among its case studies, told Fortune.

“It’s very difficult to set out to purposefully make an iconic brand,” Beverland continued. “Quality and authenticity are essential. But it’s also about good luck, being noticed by the right people, and accurately representing the culture. With Doc Martens, it helps that they can be seen as representing many different cultures.”

“Dr. Martens on your feet”

The boots’ origin story dates back to when the original Dr. Martens —Dr. Klaus Maertens, that is, a former cobbler and military medic—broke some bones in his foot while skiing a few weeks after the end of World War II. Using reclaimed material from war-ravaged Munich he made the first pair of shoes for himself, so he could walk more easily during his recovery.

Soon after, Maertens formed a company with a college friend, Dr. Herbert Funck—the shoes could have just as easily been called “Doc Funck’s”—and over the next few years they had modest success selling to homemakers and injured soldiers. In 1959, they sold the patent rights to a British shoemaker known as the R. Griggs Group, which started making the shoes in England.

The bestselling Doc Martens model has always been the first, an eight-eyelet lace-up boot called the 1460, named for the exact date—the 1st of April, 1960, as in day, month, year—the boot was first released. Last year, it accounted for 42% of the company’s sales.

But according to Martin Roach’s book Dr. Martens: The Story of an Icon, the shoes really became embedded in popular culture when Pete Townshend, the windmilling guitarist from The Who, began wearing them during performances in 1966.

Townshend, who said the boots were perfect for running and jumping across the stage, wrote a song, “Uniforms,” that mentioned his favorite boots:

It don’t matter where you’re from/What matters is your uniform/Wear your braces round your seat/And Dr. Martens on your feet.

IPO splash

Nowadays, Doc Martens boots and shoes are popular among groups that wouldn’t know Townshend if he walked among them sporting shiny new DMs. And there are a lot of those groups: The company says it sells nearly 12 million pairs a year in 60 different countries. It is building a supply chain with the capacity to deliver 20 million pairs a year by 2023 to meet the heightened demand. Revenue last year was £672 million (just under $950 million), nearly double the figure from two years earlier, and it’s likely to keep growing at a fast clip, equity analysts say.

Parent company Permira—the investment firm that acquired the R. Griggs Group in 2014—took the company public in January on the London Stock Exchange; the listing was massively oversubscribed as institutional investors nearly trampled one another to get in early. On May 7 afternoon, Dr. Martens PLC shares were trading at £4.82, 30% above its listing price. That values the company at £4.7 billion (more than $6.5 billion).

Dr. Martens’s annual revenue of £420,000 ($585,000) per employee ranks it in the top third of the London Stock Exchange’s FTSE 250 index by that measure. Metrics like that caught the eye of BofA Securities analysts, who forecast double-digit sales growth through at least 2024, far outpacing a footwear peer group that includes Crocs and Skechers and luxury peers like Burberry or Moncler.

BofA sees Dr. Martens as a potential post-lockdown star. “We expect a reopening benefit in FY ’22, and forecast 19.1% revenue growth,” analysts wrote in a March investor note. “Long-term revenues should be underpinned by strong e-commerce growth…and retail store rollout.”

BofA’s target price for the shares represents a 21% upside from May 6’s close.

Alongside the queen

Even with all the stock market buzz, the iconic stompers are hip as ever as a cultural symbol.

Rebecca Shawcross is senior shoe curator with England’s Northampton Museum and Art Gallery—about halfway between London and Birmingham, in the heart of the country’s historical shoemaking region.

The museum’s collection of more than 15,000 pairs of shoes and more than 60,000 shoe-related items includes an Egyptian sandal dating to 300 BC and the tiny silk slippers Queen Victoria wore in 1840 when she married her consort, Prince Albert. The museum’s collection also features about a hundred different pairs of Doc Martens shoes and boots, and a lot of related memorabilia. “You couldn’t have a proper shoe collection without Doc Martens,” Shawcross said.

She told Fortune that Doc Martens’s utilitarian, no-nonsense look has likely been key to the product’s remaining relevant for so long because it allowed anyone—from gritty mohawk-wearing punks to the Spice Girls and from runway fashion models to elderly members of the U.K. Parliament—to claim them as their own.

“The shoes are like a blank canvas, limited only by imagination,” Shawcross said. “Each group can see them in their own way.”