[4] Valli was the daughter of merchant Robert Alexander Knust (1861 – c. 1918) and Louisa Emily née Fowell (1862–1950).

She returned to London's Drury Lane Theatre, performing the role of the dancing doll in a pantomime version of Cinderella the following Christmas.

A strikingly beautiful woman, Valli played mostly in England thereafter, appearing in The Queen of Hearts, Purple Road and The Duke's Motto, among other pieces.

Her other screen credits are for appearances as Mary Page in The High Road (1915), Beth Coventry in The Woman Pays (1915), and Marian Delmar in Her Debt of Honor (1916).

In 1917, she married Louis Dreyfus, head of the music publishing house Harms, Day and Hunter, later owner of Chappell & Co. and later a theatrical producer.