People John Sinclair, 11th Earl of Caithness peoplepill id: john-sinclair-11th-earl-of-caithness-1JS1EOC 2 views today 2 views this weekD. 1789John Sinclair, 11th Earl of CaithnessBiographyAlso ViewedThe basicsQuick FactsIntroD. 1789GenderMaleDeath8 April 1789 People who died on this dayFamilyMother:Barbara SinclairFather:William Sinclair of Rattar, 10th Earl of CaithnessListsJohn Sinclair, 11th Earl of Caithness is in following lists comments so far.CommentsJohn Sinclair, 11th Earl of Caithness