Then you're not as old as me. 300 ohm ribbon was pretty common in Australia, especially on crappy bunny antennas. You'd need a 300/75 ohm matching balun before feeding it into the TV.

Ah, sorry I hadn't even considered that it would be different in other places (just times) - I'm in the US, and those flat ones were present here at least as late as the 1980s and likely 1990s.

Cable Internet is very common in the US, in fact the most common kind. (2nd is DSL) So the F connectors (didn't know that name) are everywhere. Also still used for actual antenna connections.
I am not sure if I have ever seen a Belling-Lee, but RCA used to be extremely common here until HDMI took over that role. (In fact RCA is what is on the switch box above to connect to the 'computer')

We had 300 ohm ribbon back when we had VHF TV. When we went to UHF in the '90s we also changed to coaxial cable

Coaxial cable works better at higher frequencies than 300 ohm, but needs shielding. 300 ohm doesn't need shielding as any wave that hits it hits phase and anti-phase at the same time and has no effect

We had flat ribbon. We used that exact unit for the atari. You screwed them into the back.

The typical ol' "garage" b&w tended to have them too, last tv i owned with one was this century