Amusingly enough ladies dressed kind of scantily in the Regency Era, particularly when compared to other eras after it. The fashion of the day was meant to emulate Grecian art and most ladies wore simple, form-fitting muslin gowns. If they wanted to be particularly daring they dampened down their petticoats to make sure their dresses clung to their bodies.

... Course they didn't wear short skirts either!