She was born in 1886, married Alan Ian Percy, 8th Duke of Northumberland, in 1911, had six children who all reached adulthood, and died in 1965. Her article in thepeerage.com is here.
Hats were beginning to become wide in 1906 as seen in this feathered example worn by Lady Helen Gordon Lennox.
Keywords: 1906, Helen Gordon Lennox, Gordon Lennox Family, Percy family, Duchess, Lady-in-Waiting, Queen Mother Elizabeth, British, bouffant coiffure, high neckline, collar, lace, bows, necklace