I think Graham, when he coined the expression, had in mind those barbel anglers who fish with very traditional methods and condemn anyone who doesn't follow likewise.
So it's spilt cane rods (no more using them for pea sticks), centrepin reels, maggots/meat/cheese pastes as bait, no high protein boilies or paste mixes, floppy hats, ill-fitting pullovers, plus fours, polished brogue shoes, Argyle socks and grow a beard.