Do you happen to know where the spiral staircase was, and what
happened to it?

The is a "lift shaft" type area located between the platforms towards
the middle. It's now a pump room (the pump was prone to fail not so
long ago, causing flooding on the platform). As others have said, the
escalator shaft towards Broad Street was located at the west end of
the platforms, up some stairs and along a passage, coming out where
the bus station now is.

So I assume its been capped now at the ticket hall level, so that they
can have that newer set of escalators to the north?
But is the shaft completely blocked up, or can you still get to it
from a newer staircase, as, perhaps, an emergency escape?

What is it pumping out? (obviously water, but where is it coming from
in such heavy quantities to cause flooding - does the walbrook pass by
there?)