LONDON — “We sat down with five or six other little galleries and went to the pub and asked, ‘How’s it going?’ ” said Tot Taylor, co-founder of the contemporary art dealership Riflemaker, recalling a meeting he had in 2012 with a group of fellow London gallerists. “Everyone said, ‘Not very good.’ ”

Mr. Taylor said he had then asked his colleagues if there was one big thing that had changed. All of them replied that fewer people were visiting their galleries. Why? “We just don’t know,” they said.

Five years later, in September 2017, Mr. Taylor’s gallery, situated in a 19th-century gun maker’s shop in the Soho district of London, joined the art world’s ever-lengthening list of small and midsize dealerships that have closed.

Founded in 2004, Riflemaker was one of a crop of London galleries that sprang up when the generation that became known as the Young British Artists, or Y.B.A.s, was in vogue. The Soho gallery’s entire inaugural exhibition, devoted to more than 450 drawings by the imaginary artist “Naomi V. Jelish” (an anagram of Jamie Shovlin, who made the works), was bought by the British collector Charles Saatchi for 25,000 pounds, about $45,000 at the time.