London, Ont, the seat of Middlesex County, is centrally located in the southwest peninsula of the province, on the Québec-Windsor corridor midway between Toronto (185 km) and Windsor (190 km). Due south lies Lake Erie, with Lake Huron to the northwest.

London's market and service area to the north and northeast includes much highly productive farmland. To the southwest and southeast lie intensive cash-crop areas, especially Canada's main tobacco-growing area. Noted as a financial, educational and medical centre, London is also a regional base for business firms and government, both provincial and federal. Economy London's hinterland contains much of Canada's most productive agricultural land, while the city's regional centrality is constantly being strengthened by improved communications. Over three-quarters of the labour force are in the service industries. Trade is the next important sector of the economy with nearly 20% of the labour-force with the remaining sectors of nearly equal importance.