She was Mistress of the Robes to Her Majesty Queen Alexandra from 1913 until Alexandra"s death in 1925. She was a Justice of the Peace for Nottinghamshire. They had three children: Lord Francis Morven Dallas Cavendish-Bentinck (27 July 1900 – 22 August 1950) Winifred Cavendish-Bentinck, Duchess of Portland, was interred at the traditional burial place of the Dukes of Portland in the churchyard of Street Winifred"s Church at Holbeck.
The Duchess of Portland was a passionate animal lover, who kept stables for old horses and ponies, as well as dogs needing homes.
In 1891, she became the first (and longest serving) president of the Royal Society for the Protection of Birds and was vice-president of the Royal Society for the Prevention of Cruelty to Animals. She was also president of the ladies committee of the RSPCA. She was elected to be the third President of the Nottinghamshire Beekeepers" Association in 1907.
She also sponsored a miner, with an interest in art, to study in London. In 2010, a collection of jewels belonging to the Duchess was auctioned at Christies, including antique pearl and diamond brooches, and the Portland sapphire tiara.