This Princess Diana photo contains
boater, leghorn, panama, panama hat, sailor, skimmer, straw hat, fedora, felt hat, homburg, stetson, and trilby.
There might also be
pith hat, pith helmet, sun helmet, topee, topi, street, city scene, urban setting, dress hat, high hat, opera hat, silk hat, stovepipe, top hat, topper, and beaver.