Manx Genealogy

Alexander Bonnyman - background

Hi everyone, I'm trying to locate background information on Alexander Bonnyman for my family tree and can't seem to find anything prior to his service as an agent for the 4th Duke of Athol. Actually aside from the Radcliffes (Mary and Jane) that he'd married and their children I haven't really been able to find much on him. I'm intersted to find out more about his life on the Island and in service to the Duke and also how he came to be in service to the Duke and to locate any solid leads on where he came from (at the moment simply some references in material on the Radcliffes on this site about him being from Banff).

So far:
Alexander Bonnyman
Born about 1763 [uncertain] in Banff, Banffshire [uncertain]
Husband of Mary (Radcliffe) Bonnyman (1770-1806) — married 23 May 1795 in Andreas, Isle of Man
Husband of Jane (Radcliffe) Bonnyman (1787-1878) — married 23 Mar 1807 in Michael, Isle of Man
Father of George Bonnyman, Mary Ann Bonnyman, Radcliffe Bonnyman, Elizabeth Bonnyman, William Murray Bonnyman, Betsy Bonnyman, Elizabeth (Bonnyman) Curphey, Catherine (Bonnyman) Luckman, Alexander Bonnyman, Maria (Bonnyman) Cubbon, Anna Frances (Bonnyman) Boscow and Sarah Bonnyman

Land agent for John Murray, 4th Duke of Atholl, KT, PC, FRS (30 June 1755 – 29 September 1830) who was governor the Isle of Man (1793-1828).

A reference stating (in regards to the Duke) "His chief agent or * Seneschal,' was James McCrone,* who did for him some of the ' unpleasant ' work. A more humane official was Bonnyman, who occupied a part of the family house at Port y Shee, and who was buried at Kirk Braddan in 1825." from a book: Island heritage : dealing with some phases of Manx history by Cubbon, William.

Thanks for any assistance anyone can provide :)