Disc-braked EMUs in Britain started in 1965 with the AM10s (cl.310s), albeit with EP not with three-step... and if I correctly recall were retro-fitted with a quite primitive WSP. Makes the 321s really hi-tech by comparison 😂 If only it was still politically correct to select step 3 at the normal braking point, then use 2 or 1 after speed is greatly reduced - booked journey times would come down to what they were in the 1980s!
