Sham 69 was (is) a British punk band, founded and led by Jimmy Pursey in 1976 with a constantly floundering line-up. They were a big influence on the Oi! movement, and made some really great singles (and one great album, The Adventures Of The Hersham Boys in 1979) in their first years. "If The Kids Are United", released as a single in July of 1978 is their rallying cry and possibly most famous and revered song, a plea for unity and friendship amongst (disenchanted) youth. Sorry about the poor picture quality of this clip, but it's a fabulous song and you're able to hear that.
Watch and listen