Simplify the following text for a Grade 10 native English-speaking person.
Original: His great-grandfather Charles Blair had been a wealthy country gentleman in Dorset who had married Lady Mary Fane , daughter of Thomas Fane , 8th Earl of Westmorland , and he was supported , as an absentee landlord , by a good income from slave plantations in Jamaica .
Simplified: His great-grandfather Charles Blair had been a rich gentleman who had married Lady Mary Fane , and he was supported by money from slave plantations in Jamaica .