British Prime Minister Theresa May last week made a three-day visit to China that exposed the difficulties London faces in a post-Brexit world. While seeking to reinvigorate relations between her country and China, May's visit was low-key, with little excitement or enthusiasm, a stark contrast to the pageantry that marked the 2015 visit to London by Chinese President Xi Jinping. Now, London faces two related dangers in the wake of its decision to leave the European Union: marginalization or appearing over-eager to combat that prospect.

During the 2015 visit, Xi, along with May's predecessor, David Cameron, launched what was heralded as "a golden era in U.K.-China relations." The promise of that relationship has yet to be realized. The total value of bilateral trade between the two counties is about $84 billion a year, around a quarter of Japan's trade with China. The United Kingdom is the world's sixth-largest economy but just 3 percent of its exports go to China and only 7 percent of imports are from there.

Relations have been tense since 2016, when May delayed approval of a deal that would allow China to invest in a nuclear power plant in the U.K., a move that disappointed (and angered) Chinese officials. That decision contrasted sharply with London's 2015 agreement to join the Asian Infrastructure Investment Bank (AIIB), a move that was criticized by other Western governments for putting a stamp of approval on a controversial project.