In message , Clive Page
writes

I cannot imagine why they thought they had to close City Thameslink: it
is a station entirely underground, with both entrances well protected
from the weather beneath office blocks, one in a mini-shopping mall.
The message I saw claimed there was too much ice: I'd have thought that
the only place ice could form would be on the pavement outside the
entrance. Does anyone understand this at all?

I wonder if the problem is the open-air section just south of City
Thameslink - there's a steep rising gradient on the approach to
Blackfriars.
--
Paul Terry