Founded the Mothers’ Union in 1876. Born as Mary Elizabeth Heywood in Lancashire. 1848 she married George Henry Sumner, son of C. R. Sumner, Bishop of Winchester, and a second cousin of William Wilberforce. The birth of her first grand-child inspired her to gather the mothers in the parish to provide mutual support. This Mothers Union rapidly grew and in 1896 when it required a President she was unanimously elected, and held the post into her nineties.
Her three children were Margaret, Louisa Gore-Browne and George who became a successful artist. (Though the photo we found, on Louisa's page, suggests Mary and George had another child, Effie, born 1849, who married a Heywood.)
Wikipedia notes that other sources incorrectly give her date of death as the 9th.