DAVOS, Switzerland — In the year and a half since Britain’s shocking decision to sever itself from the European Union, Prime Minister Theresa May has labored to portray her country’s future as one of glorious progress. She has described a bold new era in which Britain would look beyond the confines of Europe, striking trade deals and reclaiming its place as a global power.

All the while, an uncomfortable reality has been sinking in. Britain’s stature on the world stage has diminished, and its economy has sagged. The former colonial empire has been reduced to a lesser actor, a reality that hit home on Thursday as Mrs. May delivered a sparsely attended speech before the World Economic Forum.

Mrs. May devoted part of her speech to declaring Britain’s steadfast commitment to global trade and international engagement. But one of her primary examples of that commitment — highlighting Britain’s role in a European bloc it is actively leaving — underscored the strange moment she inhabits.

“The U.K. has been at the forefront of championing new trade deals including the E.U.’s deals with Canada and Japan,” Ms. May said. “And as we leave the European Union, the U.K. will continue to be a global advocate of free trade.”