You should find info here http://www.pbhistory.co.uk/ and also lots in British History On Line on South Mimms...as previously mentioned, the Brookmans Park newsletter has a history section to it as well and covers South Mimms, as does the Potters Bar Newsletter. I would think the pub may have been part of a manor at some time.
It's lovely round there...my oh knows it very well. Let us know how you get on.
Kerswill - Plymouth-London, Hawkes - Chiswick-West Ham,-Canada, Pitman - Essex-Kent-West London-Cornwall and possibly Florida), Wakeford - Hampshire-London