try http://www.ee.surrey.ac.uk/Contrib/manx/mannin/v6p318.htm
It would appear Angus Munn came to Peel mid 18th C.
where under Munn's has:

The founder of the Munns was an Angus Munn, who settled in Peel about 1760. He was in the Custom House, and died 1792: probably it was then that Captain Savage was made chief officer. Munn's old house still stands, but is hid by a modern house, built in front of it, and facing the sea. A brewery stood on the same property Angus Munn married Leonora Callister, one of the Callisters of Douglas Street, and had, with others, a daughter Mary, who married William Clarke, of Nappin, and a son Angus, who died at sea, 1807, on his way from Whitehaven. Angus, the younger, a few years before he died, built two houses in Crown Street. About fourteen or fifteen years ago. some men, repairing the roof of one of these houses, found a large slate, with 'A. Clarke' and date 1803 or '5 cut on it. This A. Clarke was probably a son of William, who had married Mary Munn.

re Clarkes see:
http://www.ee.surrey.ac.uk/Contrib/manx/famhist/families/awm1889/clarke.htm

An Angus Munn Cowle emigrated to US in 1841 - see
http://www.ee.surrey.ac.uk/Contrib/manx/famhist/genealgy/miom1991.htm