I was at work tonight and found two IBM MANUFACTURED IN UNITED KINGDOM 1985.
They have two-piece keycaps and one is lacking some of them but the other one have all the keycaps. BTW I found them where they put all the trash so I doubt they work but I had to get them just because I know you will like to see old stuff.
I found too that my microphone at work use PCB MX Black and have Spherical Keycaps like the ones Sixty showed us. I have to say that MX Black PCB mounted feel better than plate mounted ones, at least this ones. People looked at me with strange face when I was making a ghetto keypuller to take off the sphericals keycaps

I will make pics when possible!