I can't help but see Ottoline in the recent Maison Martin Margiela Haute Couture Collection for the Fall. It puts me in mind of the dresses she created with antique silk lampas-
Ottoline's voluminous photographs-and scrap books can be found here at the NPG.
I think she would have particularly liked the veil.
Ottoline, at left, phtographed by Beaton, and the dress she wore-