On Mon, 1 Oct 2012 20:28:44 +0100, Clive
wrote:

In message , Peter Smyth
writes
New Cross, Waterloo East, and St Pancras Low Level use letters rather
than numbers for their platforms.
Each of Waterloo East and St. Pancras I can understand as they're just
about two stations on the same sight, New Cross, I've never been to.

It's to avoid confusion with the platforms at nearby New Cross Gate.