LONDON — As they do nearly every hour of every day, a troop of Parisians arrived at London’s St. Pancras station on Wednesday morning off the Eurostar train from Paris’s Gare du Nord, a mere two hours and fifteen minutes to the south.

These particular travelers, however, were on a mission: “Operation Croissant.”

The day before the “Brexit” vote, when British citizens will decide whether to remain in the European Union, they were in London initially to pass out croissants fresh off the Paris train to convince their still-European compatriots not to leave the E.U.

But passing out food and drinks with expressly political messages runs afoul of U.K. election regulations, so the group donated the croissants to a homeless shelter instead, said Rosa Rankin-Gee, who came up with the idea for “Operation Croissant” 10 days ago.

 “Our aim was never to affect votes,” she said. “I think we’re all aware that this campaign has been incredibly divisive, that there’s been so much anger, and we just wanted to do something that had positivity and friendship at its heart.”

Rankin-Gee is a British writer who has been living in Paris for five years. She said her team includes both French and British volunteers.

 “It’s an incredibly informal gesture,” she said. “Just a coming together of friends who live on opposite sides of the channel.”

In lieu of actual croissants, the group instead distributed postcards “with a short note from a Parisian,” which might contain “a personal story about why they feel close to Britain” or “might just say hello.”

The postcards featured a play on what is perhaps the most famous painting by the surrealist artist René Magritte (1898-1967), “The Treachery of Images,” which depicts a smoking pipe suspended in space over a simple inscription: “Ceci n’est pas une pipe” (“This is not a pipe”).

Operation Crossiant’s postcards read: “Ceci n’est qu’un croissant” (“This is not just a croissant”).

“It’s not a grand political gesture; it’s not designed to spark debate or court controversy,” the group’s Tumblr read. “Quite the opposite. It’s simply an act of breaking bread.”

Approximately 350,000 French citizens currently live in London, according to Olivier Bertin, who represents Britain's French community in the Assemblée des Français à l’Étranger, a body that advises the French Foreign Ministry on matters pertaining to citizens living abroad.

 That makes it the sixth-largest French city in the world, he said.

Indeed, there are certain areas of London — especially the tony South Kensington neighborhood in the southwest quadrant of the city — that often seem predominately Francophone: There is the French Institute, a large French lycée, and a number of establishments unavailable anywhere else besides Paris.

Bertin himself has lived in the British capital for 24 years and runs a bilingual nursery school in north London as well as an art gallery. Many in the French community, he said, have come to Britain for a variety of reasons: a large number seek a more business-friendly environment, others to study at particular institutions and programs, and a few just to learn English.

“The people I know are afraid they can lose their jobs,” he said, “ and they cannot afford to stay in London without their jobs.” London has one of the highest costs of living of any city in the world.

 He said a majority of French people living in the United Kingdom wish to remain, regardless of what happens in the “Brexit” vote.

“If we remain in the E.U., I think everything will be forgotten very quickly and that everything will go back to normal as usual — I hope,” he said.

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