Canadians use many British spellings, like "favourite," eh wot? Man, are those HB/WB comics off-model, especially the hydrocephalic Wilma, and Sylvester. And yes, Top Cat was called "Boss Cat" in the UK (and "Don Gato" in Spanish-speaking countries). Pappy's Golden Age blog featured an Australian edition of Superman from the '50s chock full of such alterations... dollars to pounds, "jail" to "gaol," etc. Worst was in one of those one-page humo(u)r fillers Henry Boltinoff cranked out by the thousands in Silver Age DC titles. "Jerry the Jitterbug" wants to pick up a cute girl, but changes his mind after seeing her window-shop for furs, jewel(le)ry, and other expensive things: "I guess $he'$ not my type after all!" The Aussie publisher changed it to "I guess £he'£ not my type..." (Perhaps if they waited till 1966 when Australia changed from pounds to dollars....)One wonders why they bothered since Superman was well established as an American character.
This reminds me of the late 1990s/early 2000s when I was a Sailor Moon purist who hated the dub (actually, I still hate the dub, but I realize now that it was a product of its time) because of all of the changes that had to be made to Americanize it. These "Britishized" comics indicate that even altering a comic or cartoon to fit into another English-speaking culture really changes the content. The Flintstones comic where working class caveman Fred suddenly has aa quasi-Oxbridge-inspired vocabulary illustrates this.