Vinci SA is doubling down on budget travel with the $3.7 billion purchase of a controlling stake in Gatwick Airport.

London’s second-busiest hub has more than tripled in value since it was bought by Global Infrastructure Partners for about 1.5 billion pounds ($1.9 billion) in 2009, mainly because of the surge in low-cost tourism.

The skies looked very different when the infrastructure investor swooped on the biggest single-runway airport in the U.K. The global financial crisis had hit tourism, Ryanair Holdings Plc reported its first annual loss after a failed attempt to buy Irish rival Aer Lingus, and Norwegian Air Shuttle ASA, now one of Gatwick’s main customers, was still years away from starting its long-haul routes.

Today, budget travel is booming to destinations near and far and airlines including EasyJet Plc, which has Gatwick as its biggest hub, are increasing plane orders, said Nicolas Notebaert, who heads Vinci’s concession and airports businesses.

“Traveling is a key element of the world of today and tomorrow,” Notebaert said. “All aspects of tourism are growing.”

Vinci already owns stakes in 44 airports, many of them serving low-cost airlines in cities such as Faro, Portugal; Kobe, Japan; and Salvador, Brazil. The company, based in Rueil-Malmaison, France, is paying about 20 times Ebitda in what Matthias Volkert, an analyst at DZ Bank, described as an effort to add “more attractive and reliable margins” than in its traditional business.

Not everybody is convinced by the strategy.

Bernstein analyst Daniel Roeska said he’s not persuaded that Norwegian’s business model will hold, which is a near-term risk for Gatwick because the airline is its third-biggest customer. Main hub airports like Heathrow benefit from a broader distribution of destinations and traveler profiles, he said.

“If I was an investor, I would have to be convinced that Gatwick’s three biggest airlines, EasyJet, British Airways and Norwegian, will continue to grow,” said Roeska. “I would also need to believe that the U.K. economy and the economies of popular leisure destinations like Spain and Portugal are strong.”

Norwegian tried Dec. 24 to reassure investors on the solidity of its cash position, and has said it will sell aircraft and cut costs as disruptions in the debt-laden carrier’s long-haul flights add to difficulties during the slow winter season.

–With assistance from Andrew Noël.

©2018 Bloomberg L.P.

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Photo Credit: A Norwegian Dreamliner landing at London Gatwick. Gatwick Airport