Apologies for late response, but I'm new to Rootschat. No direct help, but I have a possible connection to Jane Manson who married William Cogle in Bower (near Watten) in 1776. Their daughter Ann married James Cardo, a soldier from the Rothesay and Caithness Fencibles in 1799. I found a copy of his military record a few years ago from the archives of the Chelsea pensioners. I believe they are now at the national archives at Kew.
Also, according to Caithness.org, the Cogle(Coghill) estate 'included the present day lands of Cogle, Gersa and Scottack (Scottag). Old records sometimes refer to the estate as "Coglefute". About 1700 the last Coghill sold the lands to Manson of Bridgend, Watten.'