Originally from Scotland, William Russell Flint was an illustrator and watercolor painter who spent much of his career in London, and traveled and painted in France and Italy.
Flint’s illustrations of literary or mythological scenes, as well as Gilbert and Sullivan operas, have a nice quality of Golden Age illustration to them.
He is also noted for his numerous rather politely erotic watercolors of nude or semi-nude young women either posing or engaged in mundane activities, seemingly oblivious to being observed.
Most notable, however, are Flint’s more straightforward watercolors painted during his trips to France and Italy. These are often of architectural subjects, and at their best, have some of the color and clarity found in Sargent’s watercolors.
Among online resources for Flint’s work are a couple of long-established sources for signed and limited edition prints. sirwilliamrussellflintprints.co.uk appears to the the official source associated with the artist’s family, but russellflint.net has a number of zoomable or clickable images at higher resolution.
Wikipedia has a selection of Flint’s illustrations. There is a nice selection of illustrations, landscapes and other subjects on The Pictorial Arts blog (search links). There is also a post on Willaim Russell Flint’s watercolor technique, with a step-by-step description of his work on a specific painting.
There is a brief British Pathé video of Flint in his studio from 1956 (thanks to James Gurney for the tip).