Mr. Choplin, who had announced that he would leave when the theater closed for renovation, also suggested Ms. Mackenzie team up with Thomas Lauriot dit Prévost, his No. 2 at the Châtelet from 2006 to 2013. Although Mr. Lauriot dit Prévost’s title is general director, he and Ms. Mackenzie said they shared all aspects of the theater’s leadership, from budget planning to artistic choices.

“We started by spending a complete day together in Brussels,” Mr. Lauriot dit Prévost said in their shared, spacious office overlooking the Seine River. “We talked about our political vision of what a theater should be in society, what our values were, what we would stand for.”

Ms. Mackenzie is the first Briton to run a French national institution and the first female director at the Châtelet since it opened in 1862. But Christophe Girard, Paris’s deputy mayor for culture, said that her nationality was never an issue during the hiring process.

“I think the fact that she isn’t French is useful,” he said. France has its own cultural and institutional norms, he added, and Ms. Mackenzie “ knows when she doesn’t want to understand , and I think she solves a lot of problems that way. Ruth knows how to use what could be a weakness and make it a strength.”