William Hamilton 1634–1694 Earl of Selkirk | | Anne Hamilton 1632–1717 Duchess of Hamilton suo jure |
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Earl of Orkney (3rd creation), Viscount Kirkwall, and Baron Dechmont, 1696 | |
George Hamilton 1666–1737 1st Earl of Orkney, Viscount Kirkwall, and Baron Dechmont | |
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Anne O'Brien d. 1756 2nd Countess of Orkney, Viscountess Kirkwall, and Baroness Dechmont | |
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Mary O'Brien c. 1721–1790 3rd Countess of Orkney, Viscountess Kirkwall, and Baroness Dechmont | |
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Mary FitzMaurice 1755–1831 4th Countess of Orkney, Viscountess Kirkwall, and Baroness Dechmont | |
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John FitzMaurice 1778–1820 styled Viscount Kirkwall | |
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Thomas FitzMaurice 1803–1877 5th Earl of Orkney, Viscount Kirkwall, and Baron Dechmont | |
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George William Hamilton FitzMaurice 1827–1889 6th Earl of Orkney, Viscount Kirkwall, and Baron Dechmont | | Henry Warrender FitzMaurice 1828–1875 | | Frederick O'Bryen FitzMaurice 1830–1867 | | James Terence FitzMaurice 1835–1917 |
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| | | | Edmond FitzMaurice 1867–1951 7th Earl of Orkney, Viscount Kirkwall, and Baron Dechmont | | Douglas FitzMaurice 1861–1932 | | Isabella FitzMaurice d. 1948 |
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| | | | | | | | Douglas FitzMaurice 1890–1937 | | Frederick St. John 1886–1977 |
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| | | | | | | | Cecil O'Bryen FitzMaurice 1919–1998 8th Earl of Orkney, Viscount Kirkwall, and Baron Dechmont | | Oliver Peter St John b. 1938 9th Earl of Orkney, Viscount Kirkwall, and Baron Dechmont |
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| | | | | | | | | | | | Oliver Robert St John b. 1969 styled Viscount Kirkwall Heir apparent |