On top of hearing about a large-scale Canada Day celebration every year in Trafalgar Square, and wandering into a "Canada Store" where you could buy Kraft Dinner, Ketchup Chips, Swiss Chalet sauce, etc... I came across these two very Canadian establishments while wandering London:
A Tim Horton's in a Piccadilly Circus(!):
And a otherwise unspectacular bar aimed at ex-pats:
London, you know how to make a Canadian boy feel welcome.