This lovely woman is the novelist Ursula Bloom (1892-1984) painted in 1932 by Charles Buchel (1872-1950). The painting is called 'Ursula Bloom on the Promenade at Walton-on-the-Naze'. Walton-on-the-Naze is a seaside town in the county of Essex, and Bloom was an Essex girl herself. In fact she often used the pseudonym Mary Essex. I'm guessing it's one of her own novels she's holding in her hand, but can't read the title. I've never read any of them and none of them appear to be in print -- is she due for a revivial?
Many thanks to Ruth for sending me the link!