Don't worry, there was far too much (changing) detail to take it all in!
I'll be interested to see what you find out about rural constables.

There is quite a bit on the internet at: www.gov.im/dha/police/1878_1888.xml

And also a "List of Police Officers - 1840-1899" on Manx Notebook which includes:
CORKILL Robert 1864 Constable.
CORKILL Robert 1871 Constable.

Sue