In message , at 20:07:35 on Tue, 29
Dec 2015, Robin9 remarked:

This afternoon I took a Thameslink train to Sutton which
arrived at St. Pancras International at the "wrong" platform.
This was clearly intentional as the train announcer warned
that the doors would open on the right-hand side. (There
was a train waiting at the other platform which seemed to be
heading for Bedford.) On our platform none of the destination
indicators listed our train or Sutton.

Is two-way running common at St. Pancras International? If it is,
why do the destination indicators not display South London
destinations?

Two-way running has to be allowed, otherwise they wouldn't be able to
turn the entire north-facing service there. Which of course doesn't
require any South London destinations to be shown.

I've never seen it though. Perhaps RTT is your friend for today's
movements.
--
Roland Perry