Dukes in the United Kingdom
Duke, in the United Kingdom, is the highest-ranking hereditary title in all four peerages of the British Isles. A duke thus outranks all other holders of titles of nobility (marquess, earl, viscount and baron).
List of viscountcies in the peerages of Britain and Ireland
A number of Speakers of the House of Commons have been elevated to the peerage as viscounts. Of the nineteen Speakers between 1801 and 1983, eleven were made viscounts, five were made barons, one refused a peerage and two died in office (and their widows were created a viscountess and a baroness). The last such was George Thomas, 1st Viscount Tonypandy upon his retirement in 1983. Since then it has had become more common to grant life peerages to retiring Speakers.