LUTON, England — It was 5:50 on a Friday morning, and most of the people at a Starbucks in the middle of a shopping concourse at Luton Airport, north of London, looked slightly miserable, as if they preferred to be somewhere else.

A man in a green hoodie sat with his chin propped on his hand, staring at a departure board. A young couple next to him looked at their phones, ignoring each other. There was little conversation, and no laughter.

A few feet away, though, at the Smithfield Pub (“Est. 2017”), which was designed to look like a wood cabin, the mood was more festive.

A couple were drinking strawberry-flavored cider to celebrate the start of a romantic trip to Paris. A woman was ordering gin and tonics and pints of Guinness for her friends, while swaying to music at the bar. Two men heading to Alicante, Spain, for a cricket tour were laughing while drinking lager.