That second wave of Mod was ridiculous. Did you ever see Secret Affair? Terrible old tripe. A cross bewteen Sham 69 and a Zombies tribute band. I remember The Chords being better and some of the more r&b oriented bands being ok but none of it was a patch on the Coventry scene.
The only personal music-related violence I suffered was at a Theatre of Hate gig (probably serves me right) at the 100 Club in maybe 81 or 82 around the time of the Oi! obsession in Sounds and again coming out of a Dexys show at the Old Vic around the same time. Oh and at a Carmel show of all things when my best mate got into a fight with one of her band.
Mods were too busy worrying about their crappy suits and horrble Jam shoes to go around fighting with people. The Casual thing that was around at more or less the same time was much more unpleasant but didn't seem to have much to do with live music unless they were all off watching Luther Vandross and Odyssey which I kind of doubt. Ever hear Bill Hicks' routine about English hooligans? Just about nails it.