I was weak and I bought something from eBay. A $47 LEGO interface A box from 1987. It has support for the BBC Micro
Amazing that before Mindstorms, #arduino or Scratch, #lego had their own hw, sw and courseware for teaching embedded systems to kids in #80s.
Someone put scans of the teacher and student materials here (non https site) http://www.mybbcmaster.nl/educ_lego.html
I think you can plug this LEGO interface directly into the BBC Micro User Port! (need to double check pins map to the right places, this box supports Apple II and others too)
@bbcmicrobot Those match the numbering in the user guide. Page 496 (Appendix K) pl10 connector.
@bbcmicrobot I love that they translated that table to each language. Paper was cheap back then?