No, I think it was when one box with multiple fuses of different values
replaced a collection of miscellaneous switch fuses - one for lighting,
one
for power, on for immersion etc.

I have never heard a non-electrician refer to any unit containing only fuses
(rather than MCBs) as a consumer unit. It is invariably a fuse box, whether
it contains one fuse or ten fuses, whether it has an isolator switch or not.
IME, DIN rail = consumer unit, Wylex/MEM = fuse box.

Christian.