Lydia Corbett, 91, is a French-English painter and sculptor who, in 1954, sat for Pablo Picasso and was the subject of about 60 works, turning her hair style into a sensation. Her upcoming Redfern Gallery exhibit in London opens on Nov. 4. She spoke with Marc Myers. [Photo above of Sylvette David, 19, later known as Lydia Corbett, on a hillside overlook…