Arthur Sinclair Peerage person ID=343080 (1780–1831) Parents William Sinclair, 1st Earl of Caithness Marjory Sutherland Children Siblings Robert Sinclair Alexander Sinclair Mariot Sinclair Susan Sinclair Katherine Sinclair Lady Elizabeth Sinclair William Sinclair, 3rd Lord Sinclair George Sinclair Sir David Sinclair Eleanor Sinclair Oliver St Clair, 12th Baron of Roslin William Sinclair, 2nd Earl of Caithness Catherine Sinclair