The term Italianate stems from the Italian villas, particularly those of Tuscany, that inspired the style. The villas were built for the Florentine elite during the Renaissance but English architects, searching for a new look, went for it in a big way in the 1800s. The fact that Queen Victoria's husband, Prince Albert, designed Osborne House in the Italian villa style helped popularize the look.
It's a giant leap from Renaissance villas and royal palaces to the Italianate homes of London, Ontario. The square towers didn't appear here at all. Nevertheless, an extremely scaled down version of Italianate become popular throughout the province from about 1860 to 1890 and London has numerous examples.
23 Peter Street, built about 1873, could be a textbook illustration of an Italianate house. The low-hipped roof, wide eaves, double brackets, and elongated windows are typical of the style. Bricks form segmental arches over the windows and doorway and there are brick pilaster strips at the corners of the building. A blue historic plaque has been placed on this house and a sign to the right of the door tells us this was once the home of Rowland Dennis, Ironmonger, in 1875. Mr. Dennis owned Forest City Wire Works, specializing in fencing, railings, crestings, finials, and stable fixtures. By 1895, his company had been renamed Dennis Wire & Iron Works.
Update, September 2015: Go look at 505 Talbot while there's still time. Sadly, even though it was listed as a Priority 1 on London's heritage inventory, this is one of the buildings scheduled for demolition by Tricar to make way for a 30-storey tower.