LONDON — Until Britain voted to leave the European Union, Philip Levine never thought deeply about his Jewish heritage.
But looking for a way to ensure that he could still work and live in Europe once Britain leaves the bloc, Mr. Levine, 35, who was born in Britain and lives in London, decided to do what some Jews, including his relatives, might consider unthinkable: apply for German citizenship.
He did so by employing a provision of German law that has been on the books since 1949 but that has been little used in recent years. It allows anyone whom the Nazis stripped of their German citizenship “on political, racial or religious grounds” from Jan. 30, 1933, to May 8, 1945, and their descendants, to have their citizenship restored. Most of those who lost their citizenship during that period were Jews, though they also included other minorities and political opponents.

He is not alone in turning to the German law after Britain’s decision to end its membership in the European Union, also known as Brexit. Since the vote in June, the German embassy in London said it had received at least 400 requests from Britons for information about German citizenship under a legal provision known as Article 116.
At least 100 are formal applications by individuals or families, said Knud Noelle, an embassy official.

“We expect more in coming weeks,” he said, adding that the embassy normally receives roughly 20 such applications every year.
The interest among British Jews is far greater than ever before, said Michael Newman, the chief executive of the Association of Jewish Refugees, who said that he, too, was considering applying for German citizenship.

The association is based in London.

“I don’t remember hearing of requests before” for German citizenship in the association’s 75-year-old history, he said. “It’s taken Brexit to do this. It was a game-changer.”

The development is among the most surprising techniques being used by British and European citizens as they seek a second passport that would allow them to retain their ability to travel, work and live anywhere in the bloc even after Britain’s departure is complete sometime in the next several years.
People from the Continent living in Britain, Britons living in Europe and Britons living at home but eager to retain the benefits of European citizenship are investigating their heritage, considering marriage, studying residency requirements and otherwise searching for legal paths to get around the effects of the British vote.

“I didn’t realize how simple it is,” Mr. Levine said of the application process for German citizenship, adding that he had done it initially for practical reasons and because his brother brought it up. “It’s literally a back door” into Europe.

Britain allows dual citizenship, and Jews interviewed for this article said they planned to keep their British nationality. They said they had no immediate plans to move to Germany, either. Rather, German citizenship would allow them to keep traveling visa-free inside the European Union and maintain other benefits of belonging to Europe.
Many British Jews, especially the younger generations, are comfortable with Germany, which they say has done enough to confront its past.

Richard Ferrer, the editor of Jewish News, which is based in London, said he did not plan to apply for German citizenship, but only because he was a “born and bred Brit.” Germany has done everything in its power to right its past wrongs, he said. “I’m very pro-German and I’m very happy with Germany,” he said.