Mary was the daughter of Alexander Hood, 1st Viscount Bridport, and his wife, the former Lady Mary Penelope Hill. She married the future marquess, then an MP and the heir to the marquessate, on 16 April 1868 at Windsor. A photograph of the couple on their wedding day was owned by Queen Victoria and is in the Royal Collection.[2]
They had eight children:
Lady Margaret Alice Seymour (1869–1901), who married James Ismay and had children
Lord Edward Beauchamp Seymour (1879–1917), who married Elfrida de Trafford
Commander Lord George Frederick Seymour (1881–1940), who married Norah Skipworth and had children
In 1884, her father-in-law died after a fall from his horse,[3] and her husband succeeded, entitling her to be called Marchioness of Hertford.
The Marchioness of Hertford died in April 1909, aged 62, while travelling to Palestine. Her husband died at Ragley Hall, Warwickshire, in March 1912, aged 68, and was succeeded by their eldest son, George.