In 1940s and 1950s noir films popularized fedora hats even more and its popularity lasted until late 1950s, when informal clothing became more widespread.
It returned in mid-1970s and again in 1980s and in 2000s. 
Hattingdon of course had to have a collection of fedoras and ended up with six in a variety of eye-catching colorways. Here she is in classic grey.
More about the fedora from History of Hats :
The fedora first appeared in 1882 as a female hat. That year was a first production of a play “Fédora” by the French author Victorien Sardou. He wrote the part of Princess Fédora Romanoff, a title role, for then famous actress Sarah Bernhardt. In it she wore center-creased, soft brimmed hat.
The hat was soon a popular fashion for women especially for women’s-rights activists.
After 1924, when Prince Edward of Britain started wearing them, fedora was adopted by men and became part of their fashion replacing bowlers, flat caps and top hats. It was primarily worn in urban areas for protection from bad weather and for esthetic reasons.