Is it generally one specific line whose platforms fill up first (which
one?), or just whichever one happens to be the most disrupted that day?

It would be a disgrace if no solution was planned. So, what is supposed
to be the solution?
--
Richard J.
(to e-mail me, swap uk and yon in address)

In my experience, it's usually the Northern and /or Picc Line platforms.
I'm usually just passing through these days, but when I was entering and
leaving the system at Kings Cross, I was scared for my life just in the
ticket hall on a number of occasions. The layout is a bit better now it has
been re-furbished, but I wonder how it will change when Eurostar services
start