It makes a lot more sense when you realise that there's a bit missing. On this page you can see a drawing of the original with an ornate centrepiece where "a central urn with four consoles offered drinking cups suspended by chains", and there's also a photo from c. 1980 of a replacement "font" in place, rather more utilitarian, but still at least raising the water from down here up to a bowl rather closer to drinking level!
GPS Coordinates:
51.45633, -2.62304
Location: Clifton