I have a very vague recollection of a 405-line b&w tv, with 26" screen size, being used at my school in the mid-'60s.
The gaps between the lines were visibly huge!
At the other end of the scale, by the early '70s, there was the fabulous little Sony 9-90UB tv...
...which had "everything": 405- vhf and 626-line uhf, mains or 12v operation, forward-facing speaker, telescopic aerial, and (on an available version) a small box on the LHS with audio/video/EIAJ connection for use as a video monitor.
The black lump on the right was a sturdy removable screen/panel protector.
Before our first colour tv at home (1974)...
...a Sony KV2000UB, the little 9" was our only tv set - such were the first few years of paid employment!
Like a lot of Sony's, the 20" soldiered on faultlessly for over 20 years. Eventually, it blew out a capacitor. This was replaced gratis by Sony (at their Staines service centre), on the basis that it was the oldest Sony tv they'd seen that year. Lovely.