Even the 20th-century wars could not close down the pubs.

“During the two world wars, sometimes there was a shortage of beer and the pubs had to close for that reason,” said Paul Jennings, a historian and author of several books about pub culture and alcohol consumption in Britain. He added that some pubs, particularly those in London, may have closed during The Great Plague of 1665, but that “there is no real precedent for closing all of them like this.”

Historically, pubs were open 24 hours a day, but that started to change in the early 19th century, when they would briefly close on Sundays for church services. Everything changed during World War I, Mr. Jennings explained, as the government at the time claimed that drunkenness was undermining the war effort. (“It probably wasn’t,” Mr. Jennings said.)

Pubs were then ordered to stay closed until at least late morning, then to briefly close again in the afternoon and to close for the night around 9 p.m. The days of grabbing a 6 a.m. pint on the way to work ended with the war, too.

Those general opening hours largely stayed the same through World War II. “Churchill was keen to make sure they still had a beer supply,” Mr. Jennings said. “It was seen as good for morale.”

During the 1980s, Margaret Thatcher’s free market government gradually removed most restrictions on operating hours, once again allowing pubs to open all day. Today, pubs operate on “agreed hours” when they apply for their license with their local council authority. Most close by midnight.