I was at the Millwall home game in 1977. I was 10 so with dad, stood in the Archers watching the Milton Road quoir and lads separated by a single thin line of policemen from the Millwall hordes. Very soon punches were flying over and between the coppers' heads between the opposing sides. Far more interesting than the game, which was a dull 2-0 I think.
Also up at Stamford Bridge same season v Chelsea, we went ahead but lost 3-1 in the end. After we scored the opener the Headhunters who'd infiltrated the Saints end waded in...dad hoisted me up on his shoulders and ran to the pitch side...