Homesick Americans can actually get that on draught here in London, at the Maple Leaf pub in Maiden lane (tube: Covent Garden). It's a pub with a Canadian theme but not much else (only real Canadian they have is Moosehead in bottles, nothing on draught; they have ads for Sleeman's but I didn't see any round there).
I have been there! On Canada Day, 2011, the Canadians took over Trafalgar Square for festivities, including a hockey rink, a charity basketball game, Mounties, and copious amounts of Sleeman's. Then we all adjourned to the Maple Leaf pub for afters. Fun place, in the context of Canada Day festivities, although perhaps not every day. Something wonderful about the idea of a pub for Canadian exiles.
To give you an idea, here's a picture of the Canada Day party...
