The Duchess of Portland died on 24 April 1844. Nearly 10 years later, Portland died at the family seat of
Welbeck Abbey, Nottinghamshire, in March 1854, aged 85. Two of their sons predeceased their parents; their eldest dying of a brain lesion and their third son dying of a heart attack. The duke expressed a desire to be buried in the open churchyard in
Bolsover, Derbyshire, near the other family seat at
Bolsover Castle. However, he was instead interred in the ancient Cavendish vault, that had previously been unopened for 138 years. He was succeeded in the dukedom by his second son (but the eldest surviving),
William. The department of
Manuscripts and Special Collections, The University of Nottingham holds a number of papers relating to Portland: His personal and political papers are part of the Portland (Welbeck) Collection while the Portland (London) Collection contains papers relating to his estate business. The Portland Estate Papers held at Nottinghamshire Archives also contain items relating to Portland's properties. ==Arms==