Yes indeed, this would make a good movie, or maybe better yet, a perfect BBC-type multi-part series (and if you bend the events of the novel a little, a multi-year series, "Vicar of Dibley" style. In Mrs. Gamart, it has the perfect villain).
On re-reading, it struck me how indebted Fitzgerald is to Muriel Spark: same slim narrative, same incisive characters, same implicit feminism. The big difference, to me, is that Spark is all steak knives and sharp edges, while Fitzgerald is all butter knives and round edges. Spark's heroines go for the glittering prizes, while Fitzgerald's learn resignation (albeit after a brief skirmish). At the end of the story, Florence "valued kindness above everything." Spark's women valued victory; they are more in line with Mr, Brundage's "Courage!" These are just differences, not necessarily superiorities on either side.
Perhaps the Spark/Fitzgerald heroine differences spring from the differing personalities of their authors. Patently Spark did NOT value kindness above everything. I look forward with interest to reading Fitzgerald's biography; at the moment all I have to go on is her photo, which suggests a kindly woman: