LONDON — When Britons voted in a referendum last week, they faced a deceptively simple question: Did they or did they not wish to remain in the European Union? When they stunned the world by saying no, their sentiments were far more tangled.

Britain’s fraught relationship with countries across the channel, dating to Roman times, is woven into this island’s DNA, binding the rousing Shakespearean battle cries of Henry V invading Agincourt in France in 1415 to the banners raised by fans in contemporary European soccer championships, also fought out in France.

Many of the emblems of identity seem to recur, built on the notion of an island nation pitted against superior forces, fighting against the odds, swimming against history’s tide.

But this time, one recurrent theme has been repeatedly invoked.

Since the 19th century, Britons have drawn a distinction between the muscular warriors keen to expand their influence in far-flung lands and those citizens — the so-called Little Englanders — happier to retreat into an insular core of mercantile self-interest.