I was amused to read this in an old copy of Wireless World.

The Hankey Committee, 1945.
"The committee, after stating that it regarded the 405-line standard as
unsuitable
for picture sizes greater than 8*10" (i.e. about 13" diagonal),
suggested that
an improved system of perhaps 1000 lines should be introduced as soon as
possible."

So it's only taken 60 years....

--
Eiron.