It is 1921, when the novel opens.
Here is an elegant lady (who could be ANGELINA, but costumed by Chanel) dressed to the nines for a walk outside. Notice how her outfit sits on her figure, and how much easier it is to move!
Compare the underwear she is wearing:
with what Victorian ladies had to wear:
and also with the Chanel outfit from 1914, which was difficult to walk in: