Sorry to say as far as I know Sir Mark left no descendants - his spinster sisters endowed the Mysore Cottages in Ramsey in his memory. Both Sir Mark and others of his family is mentioned in Mrs Radcliffes book "A History of Kk Maughold" Sir M's father Thomas being Vicar of that parish among others. His Grandfather and Great-grandfather were Captains of the parish of Marown. I have a distant connection, as Sir Mark's sister Hesther Hildesley Cubbon married my great-great-great-Uncle Robert Corlett. They had an only daughter, buried with her parents in the Cubbon plot at Maughold. She died as a young lady and never married. Therefore we have no surviving mutual relatives on that line. Interesting to hear of the Rimmer connection.