We always called them ghettoblasters in the UK too, though the small ones, and mono speaker+radio+tape like the photos of mono sets in the article, were always just "the radio" or "the tape". Ghetto blaster was for the big stereo ones. Always stereo.
Boombox was a name that came from US TV and film, and only started to be the name retrospectively looking back. I don't remember anyone here actually using boombox back then.
We used the term in the US as well, boombox was just more common and TV English. A good deal of kids called them ghettoblasters. Less commonly used but heard from time to time was JamBox and BumpBox. IIRC GhettoBlaster seemed to be used in the early 80's more where BoomBox and the others seemed to be used in the very late 80's and 90's but my memory could be wrong. I do remember when I was younger them being almost exclusively referred to as GhettoBlasters.
Boombox was a name that came from US TV and film, and only started to be the name retrospectively looking back. I don't remember anyone here actually using boombox back then.