For genealogists one of the primary sources for research is the local newspaper. Increasingly many of the major dailies are finding themselves online. Lots of luck for the newspapers of Middlesex and Elgin Counties. How are you with 20th century technology?
For Elgin County the Elgin County Library has microfilms of the St. Thomas times Journal, the Dutton Advance, and the West Lorne Mercury Sun.
For Middlesex County the London Public Library has microfilms of the London Free Press, the London Advertiser, and other smaller papers that were published in Middlesex County. The best and most complete microfilm collection is to be found at the University of Western Ontario. They just about have everything; however, be prepared to write notes as they will not copy any pages for you. For some reason the West Lorne and Rodney papers were put in the regional room separate from the other microfilms, and has gone missing. Darn they will steal anything nowadays!!