When Sadiq Khan vowed to be London’s “most business-friendly mayor” ever, he perhaps did not anticipate that his countrymen would, just a month after his May 2016 election, vote in business-unfriendly fashion to leave the European Union.

In the day following the stunning Brexit vote—which seemed to many, an act akin to sliding the world’s financial capital under an economic guillotine—the British pound plunged and business leaders like JP Morgan’s Jamie Dimon were forced to more seriously consider threats to relocate thousands of London jobs to places like Frankfurt or Dublin. (For his part, Khan asked the global business community not to panic and stressed that the one million Europeans living in London were welcome there.)

It’s unclear when (or even if) that blade will fall, and how sharp it will be. But while the specter of Brexit makes Khan’s job tougher, he’s doubled-down on his vision of a London that is as bright a place for business as it has ever been. In the weeks after the referendum, he launched a campaign, which like many in 2016, has a hashtag—#LondonIsOpen—and a YouTube video.

Under that banner, Khan travelled to Paris in late August. This week, the mission brought the charismatic mayor to New York, where amid a packed schedule—a Mets game, the Clinton Global Initiative, an off-Broadway production of Sweeney Todd—he dropped by the Chelsea headquarters of WeWork, the co-working company and unicorn, to pitch entrepreneurs in the “world’s second greatest city” on the first. (Sorry, Bill de Blasio.)

“London has been open to people, trade, and ideas for more than 1,000 years and that is not going to change,” he told the group of startup types. He went on to praise London as a source of talent and a hub of everything.

Khan was talking to a friendly crowd: London is WeWork’s second largest market, and after welcoming Khan as a member of the “We Generation,” WeWork founder and CEO Adam Neumann, announced his company’s plans to open to two more co-working sites in the city. Rich Riley, CEO of London-based Shazam, the company behind the music identification app, was also on hand to talk up the city. Shazam’s 100 London-based employees represent 30 countries; despite the potential implications of Brexit on hiring, Riley remains “optimistic.”

London is the top hub for tech companies in Europe, and Khan is determined to keep it that way. He travelled to North America (he also made stops in Chicago and Montreal) with a delegation of 30 London-based entrepreneurs and his Deputy Mayor of Business, Rajesh Agrawal, a self-made fin-tech entrepreneur of Indian origin, whom Khan had appointed in part because, as he told the crowd at WeWork, “he speaks your language. That’s what’s important for my city, for New York, and for the next generation.”

In some ways, though, it’s an awkward time for the Khan to be courting U.S. startups. Earlier this month, he announced a set of policies that will boost London’s black cab industry; Uber, which contends they are discriminatory, is challenging them in court and attempting to rally support from the public and startup community.

The London-based entrepreneurs participating in the trade mission didn’t seem to hold it against Khan. “The politicians are in a sticky place,” says Damian Hamp-Adams, CEO of Rocketseed, a London-based email-branding firm with an office in Trenton, NJ. Like others in the delegation, he was looking to make connections and grow his business in the U.S.

For his company, Brexit uncertainty at home has pushed him to more quickly expand across the pond. “Right now, there’s an aura of everything is ok,” says Hamp-Adams. “And I think it is to a degree it is. London as a survivor and place to do business is fantastic. But for a business like us, we reformed our strategy June 27 to focus more on the U.S.”

Few others seemed to be sweating the vote’s implications just yet: “Entrepreneurs find ways around problems,” says Emma Sinclair, co-founder of London-headquartered Enterprise Jungle, an HR software company.

Alain Falys, the French co-founder and CEO of London-based YoYo Wallet, a mobile payment company shared the sentiment though admitted that if Brexit leads to restriction on the free movement of people into London it will be an issue for tech companies like his. “London needs talent from all over the world. We all need to hire people from abroad.” Of the six engineers he hired last month, only one was from the UK.

Agrawal, Khan’s newly appointed deputy business mayor told Fortune this is one of the concerns he hears from companies. Access to the single market and regulatory equivalence are the others. Though he didn’t have clear picture of how Brexit will sort itself out, he’s confident London will remain at the center of the business universe. “It’s such an important city…The fundamentals are so strong.”

Recent survey data—compiled by London & Partners, the city’s official promoter—supports that case. In a post-Brexit-vote poll, London remains the most attractive destination in Europe for entrepreneurs. Moreover, the capital has continued to draw investment: since the vote, London tech companies have attracted $425 million and 33 deals—more than Dublin, Paris and Amsterdam combined, according to London & Partners’ data.

Still, much of the confidence in London’s future seems to ride on its legacy of openness—of which Khan is a near-perfect embodiment. It’s hard to imagine a city led by such a worldly progressive—Khan is the son of Pakistani immigrants, London’s first Muslim mayor, and a self-proclaimed feminist—slipping from its pedestal of global import. In fact, Khan expects that in an increasingly connected world, London’s stature will only grow. He subscribes to the theory that a new world order is taking shape: rather than nation-states, he believes the 21st century will be dominated by global cities, like London and New York. “That’s where the action is,” he said, before encouraging the crowd, again, to come visit.