The BBC didn't have copyright statements at the end of the credits until the early 1970s, and initially they used Arabic numerals, but after a couple of years later (the mid/late 70s) switched to Roman numerals, which they've stuck with since. I think the changeover is around the time end credits and channel logos stopped indicating "Colour".

IIRC in 1999 one of the trailers for the BBC's millennium coverage involved years counting up to MM in Roman numerals, which seemed perhaps to be a nod to their use of them in credits.