Snapshot answer They’re seaside saunas made out of old horseboxes, which have become something of a craze. For £12.50 a pop, the Beach Box Spa in Brighton (pictured) will let you swelter at 110C for 45 minutes while someone gently beats you with birch branch whisks. Small sweatboxes are so popular that there are now around 50 of them from Cornwall to Aberdeen, with dozens more on the way.
