Interesting question!
1970's
When the Shed could be bothered to make the effort we had a great firm, but most of the time individual mobs went their own way. The Shed was taken regularly in the late 60's/early 70's by West Ham and Arsenal, mainly because we had no real organisation. Apart from those two home fixtures things were pretty quiet in the Shed unless some other mob fancied their chances, which was something of a rarity. I was only young then, but I took to watching home games from under the old North Stand, much more interesting!
Away games in the 70's were a bit of a mixed bag, most games we'd take a large mob and nearly always try to infiltrate the home end. But now and then you'd find hardly any Chelsea had travelled at all and just a handful of us were there, but luckily this was pretty rare. Chelsea rarely took numbers to Old Trafford, Anfield or Goodison, which was annoying, though things picked up in the second half of the decade. A couple of seasons in Div.2 were great fun, and the mob started sticking together more, getting better organised.
1980's
Times were changing, the old bill were starting to get on top of things and getting in away ends was more difficult. Luckily the Chelsea mob had a lot of game youngsters coming through the ranks, and we were taking thousands of chaps to away games. In Div.2 most home firms didn't want to know and were totally outnumbered, we had a great time! After our promotion in 1984 a lot of Div.1 mobs were taken by surprise by the Chelsea firm, they hadn't played us for a while and things had changed. I'll see if I can rustle up memories of individual matches from both decades later on.
I stopped going in the mid 80's, when I moved away from London, so can't comment on our later mobs. In my opinion, I feel that our mob was at it's peak in the 80's, due to sheer weight of numbers, better organisation, and more bottle. That's taking nothing away from the 70's mob, and it's a close run thing. Personally I preferred the 70's, though I can't really explain why. Maybe it was more exciting because I was younger?