Re: When I was a kid
Degaussing circuits were not in late '60s and early '70s valve TVs. These would often, over time, acquire a permanent magnetic field around the chassis or the tube itself, leading to psychedelic colours at the edges of the screen. You got a TV engineer out with a magical degauss coil that he waved over the screen to make it work properly.
To compensate for the earth's magnetic field, these TVs actually had small bar magnets mounted on the chassis around the tube on bendable 'stalks'. These would be painstakingly adjusted until the Test Card showed no distortion.
My mother was obsessed with keeping a cabinet TV. They used to rent a Baird from Radio Rentals right from when BBC 2 first started transmitting in colour (around 1967 IIRC - That was a bad year for me because of illness, and I was off school for some time, and I got hooked on the Trade test transmissions which were broadcast on the hour for the benefit of TV installers - White Horses, Skycrane, and trout farming come to mind). Towards the end of it's life in the '80s, the tube was so badly magnetized that it would not demagnetize, no matter how many times the degauss coil was passed over the TV. Of course, it could be that Radio Rentals no longer had any working degauss coils in their toolboxes!
Eventually, Radio Rentals pleaded with my parents to stop calling in faults and let them take it away, because they could no longer fix it. They provided a Ferguson in it's place, which just did not hack it with my mother as it was made from paper covered chipboard, rather than real wood!
Right up until the end of her life, my mother still complained that the sound and colour(maybe because it was not psychedelic!) of whatever TV they had was poor compared to the Baird TV. I think it was an ideological thing, however, as this was even with the sound passed through external amplification.