Close by Westminster Bridge and the Houses of Parliament, there stands the statue of a woman brandishing a spear. Erected in 1902, it portrays Boudicca, the warrior queen who, in the words of the inscription on the statue’s plinth, “died A.D. 61, after leading her people against the Roman invader.”

As Britain prepares to vote next month on whether to leave the European Union, the story of Boudicca serves as a reminder that the tradition of British euroskepticism is an ancient one. Her statue, complete with rearing horses and a chariot armed with scythes on its hubcaps, seems to capture the spirit of Brexit.

It is also a reminder, though, that belonging to a European superstate can bring benefits as well as drawbacks. The location of Boudicca’s statue, in the heart of London, right by the seat of government, is not without its ironies. It was the Romans who founded the British capital: Londinium.

Boudicca’s sole contribution to its development was to massacre its inhabitants and raze it — a calamity for the city that ranks with the Great Fire and the Blitz. Although her uprising was soon crushed by the Roman legions, her presence next to the Houses of Parliament is, in a sense, as inappropriate as a statue of Sherman would be outside the Capitol in Atlanta.

How do the British principally identify themselves: as an island nation or a European people? This question, which lies at the heart of the referendum on whether Britain should quit membership in the European Union, is one tortured with ambivalences. ...