The following list is of proposed Dukedoms of the late 19th and 20th centuries that never eventuated.
Title Who for Year What happened.
Duke of Salisbury Marquess of Salisbury 1886, 1891, 1901. Offered by QV and KEVII and declined
Duke of Kerry Marquess of Lansdowne 1891 Queen Victoria proposed Gladstone stopped it
Duke Roberts General Roberts 1900 Queen Victoria proposed
Duke of Linlithgow Earl of Hopetoun 1900 Made Marquess in 1902
Duke of Chelsea Earl of Cardogan 1902 Edward VII proposed as Coronation honour?
Duke of Kent Prince Arthur of Connaught 1912 Possibly thought family had enough Dukedoms
Duke of Curzon George Nathaniel Curzon 1923 Baldwin proposed, George V stopped it
Duke of Dover Winston Churchill 1955 Offered by Elizabeth II, declined by Churchill