The late Victorian pinched waist gave way to the S shape.
This was the Edwardian view of an ideal figure. The corset forced the chest forward as a single bust and the hips back, producing the 'S' shape.
However as we can see from the bather on the right, the body became conditioned and the S stance persisted, even when uncontrolled.
Photo top left Postmarked Jan 23rd 1909