I think every TV-viewer in North America has encountered English cartoons at one time or another, but different cartoons, at different times, on different channels. The place where I got most of my exposure to British TV cartoons was on TVOntario, which used to show a lot of 5- and 10-minute Brit-toons in between the Canadian shows. The ones I saw a lot were "Jamie and the Magic Torch" (a psychedelic, Sid and Marty Krofft-ish cartoon; I lost interest when I realized the hero's name was spelled differently than mine), and the semi-famous "Simon in the Land of Chalk Drawings." The stop motion show "(Most Surprising) Gran" also turned up sometimes. And of course they had the full half-hour cartoon "Dr. Snuggles," though that was a British-Dutch co-production.
My favorite show of this bunch was not British at all, but a U.K.-dubbed version of the French stop-motion show Colargol. The version I saw, and loved, was the second dubbed version, where he was named "Jeremy."
Of the U.K. cartoons, my favorite was Willo the Wisp, with Kenneth Williams doing all the voices and the late Nick Spargo writing and directing. I still like that one. British TV cartoons had their ups and downs, but at their best they had a trippy absurdity that U.S. kids' cartoons weren't allowed to have at the time, and they could even fit in a little bit of political and social commentary: "Evil Edna," the most popular and famous character, was both a parody of Margaret Thatcher and a warning of the dangers of letting TV control your life.
This is the episode I watched most often as a kid, and the Pong joke still works for me. Pong jokes usually do.