Catherine Sinclair Peerage person ID=102125 Parents William Sinclair, 1st Earl of Caithness Marjory Sutherland Children Alexander Stewart Margaret Stewart Siblings Robert Sinclair Alexander Sinclair Mariot Sinclair Susan Sinclair Arthur 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 Partners Alexander Stewart