Children wearing calipers, older people with rickets, people (smokers) with yellowed fingers, upper deck ceilings yellowed through exposure to nicotine, children with spectacles with one lens blacked-out/covered by elastoplast, children/youths playing with clackers, people eating Tudor/Smiths/Golden Wonder crisps, women - especially under 40 - wearing head-scarves, people listening to their Sony Walkman, "dudes" carrying their "ghetto-blaster" on their shoulder up to the upper saloon, speakers for Sounds-in-Motion sound advertising, advertisements for knitting wool (there used to be a particular brand that was regularly advertised on Yorkshire WD buses), people at the front of the upper saloon opening the cover to the destination blinds and having a curious/crafty look/turn-of-the blinds where these were designed to be changed from the upper deck.
Has tungsten lighting been mentioned?
Cave-Brown-Cave heating, or Smiths heating, or Clayton-Dewandre heating.
Autovacs.
Those opening flaps at the rear of the upper saloon for use with the Cyclone vacuum cleaning system.
Pay-as-you-leave - used to the the case in Guernsey for journeys from Town, until at least the 1980s I think . . . and also used by some NE independents. (Touch-n-touch-out doesn't count.)
Change-dispensers positioned high-up by the drivers left shoulder from where the coins rolled down a chute into a cup on the cab door - Halifax/Calderdale and Leicester both used this system (was it a coincidence that Geoffrey Hilditch was GM of the former and then the latter?).