Thank you.
I was aware that he was not a Chief Constable in the modern sense. I have seen several references to him having 2/3 special constables. I am presuming these may have been volunteers. I love the analogy of the Old western films. That was definitely what I had in mind, particularly with him being known as the 'thief catcher'
I agree with your probable baptism record, particularly as one of their children is named Jane Wilson Gunn. The Kerr's seem to be quite a big family in Ayrshire. The Gunn's however are a bit more elusive! Someone suggested a few years ago that Angus may have part of the Gunn Clan of North East Scotland, but I can't find a connection as I can't even track down his birth/death dates!
I do have Elizabeth Gunn as their oldest child but have her born c 1817. She married William Gibb in 1835. May have to go back and check her a bit more....
Angus was my 4x great grandfather and my only Scottish line, turns out he almost as tricky as my Irish in laws