Circa Waves are a British indie-rock band from Liverpool, and their place on this list is a borderline, in-progress one. They are very much an active, working band with a string of albums and a loyal live following, the opposite of a closed-book one-hit act, which makes their appearance here a matter of measurement rather than verdict.
Their breakout, "T-Shirt Weather", released in 2014, is a bright, fizzing indie anthem about young summer days, and it became their best-known song by a clear margin, a festival and radio favourite.
On streaming, "T-Shirt Weather" sits near 153 million plays, while their next most-streamed track, "Movies", trails at around 29 million. That puts the ratio just past 5, over our line.
So by our strict, numbers-only measure, Circa Waves currently register as a certified one-hit wonder, and we note it is a borderline case. This is an active band with a deep catalogue and a committed audience, sitting only a little past our threshold. A single future hit could easily move them off this list, and we would not be surprised to see it happen.