However, the death of Sellar's father in August 1817 meant that he inherited a rental of about £1,000. With this extra income available, he applied his enormous energy to sheep farming and soon became much respected in the industry. He was a major tenant of the Sutherland estate, and he continued an extensive correspondence with them over the details of his tenancy. Further clearances added to his property in 1819, but he was specifically forbidden to take any part in the clearance activity. Sellar died in Elgin, Moray in 1851 and is buried in Elgin Cathedral. Sellar had a number of children with his wife Ann Craig of Barmakelty including:  His grandson was the humourist Walter Carruthers Sellar who wrote the book "1066 and All That".