Her Wikipedia article is here. A portrait of her when younger can be seen here.
This is an interesting dress, especially for the 1730s. It looks like a flashback to the 1630s with its multiple lace collars.
Keywords: Hudson, Diana Spencer (1710-1735), Duana Russell, Duchess of Bedford, Spencer family, Russell family, Duchess, British, wavy coiffure, collar, vee neckline, lace, bodice, partlet, square neckline, puffed over-sleeves, puffed under-sleeves, necklace, theatrical dress