Page 563, 564, 565 – John, twelfth Lord Sempill, the eldest son, succeeded his father in 1746 and died at Sempill House 15 January 1782. His testament, dated 14 January 1782, was confirmed by his eldest son 14 March 1782. He married 10 March 1755, Janet, only daughter and heiress of Hugh Dunlop of Bishoptoun, co. Renfrew, and by her, who died 26 June 1809, had issue:-
1. Hugh, thirteenth Lord Sempill
2. George
3. Patrick
4. Sarah
5. Janet
6. Joanna