I've often wondered how the mains coped in the UK during peak viewing times with huge chunks of current taken only in the positive cycle. Colour sets would have been worse, and with more 3 pin plugs being used by the time they appeared in 1967 it must have had an effect.
We had 10 VHF channels to start with in Band 1 & 3, operating on 625 lines & 5.5MHz sound IF as used in parts of Europe. In fact, Australia was the first place outside Europe to use this standard, now known as "system B".
Then, in 1961 it was decided that ten channels was not going to be enough for the expansion of TV into rural areas. So, three extra channels were added; designated 0, 5A, and 11. They were given these designations so the channel numbers on existing sets in capital cities would stay as they were. This was to prevent confusion to existing viewers and so stations wouldn't have to change their logos. (In Australia the viewing public knows TV networks by the channel number they transmit on).
In order to fit these extra channels in, they were put in Band 2. For here in Australia, there was a very anti FM movement by the existing commercial AM broadcasters and our excessively conservative PMG (Postmaster General) Department. There was only an "experimental" FM service run by the ABC (our government broadcaster, equivalent to the BBC) which was merely a simulcast of existing AM programs. It was shut down in 1961. Not until 1974 would Australia have FM radio again. As a side issue, given the FM band had been allocated to TV, it was proposed that if and when FM radio started up again it would be on UHF. Local industry would have loved this captive market! But with the amount of imported FM receivers in Australia by 1974, the UHF idea was canned and FM radio simply coexisted with the TV channels in the 88-108MHz band.
With FM radio really taking off in the 80's, all new TV channels were placed in the hitherto unused UHF bands 4 and 5, and areas near capital cities using Band 2 TV channels were also gradually shifted onto UHF.
300 ohm balanced transmission line was standard from day one. I suspect this was because our TV practice largely followed the US (in the monochrome era). In fact many of our sets were based directly on US designs but obviously with changes to the IF and channel frequencies. We therefore had a mixture of American and European valves in our sets. Also, as our transmissions were all horizontally polarised there was no need to use 75 ohm coax. The negative modulation system with FM sound also has less of an interference problem. (Having said that, it's a shame the 405 line system was shut down in the UK...the simplicity and economical use of bandwith had a lot going for it)
It is interesting to note the UK tended to favour separate band 1 and 3 aerials with a diplexer for 405 lines; whereas here it was always one multiband aerial. I don't know if that's in part due to our transmitters always being co sited for any given service area. Nevertheless, we did have some UK aerials of the "Antiference" brand (later produced by the local Hills Industries company). Most aerials were US designed "Channel Master" though.
Coaxial cable and those wonderful Belling Lee plugs didn't really come into fashion until the mid 70's. A lot of the public were duped into buying new aerials and transmission line when colour started, even though most didn't need to.
These days 300 ohm ribbon is seldom seen except on old installations that have survived away from the coast. It's virtually impossible to buy new any hardware for it such as mast standoffs, but I do prefer it for low loss on UHF. Even the Belling Lee plug has its days numbered with the US style F connector being preferred for new installations; especially for digital TV.
