On Tue, 2 Dec 2008 13:03:35 -0800 (PST), D7666 wrote:

I'm probably wrong but I thought mirrors are an aid to driver to see
guard but DOO needs CCTV ?

DOO requires a clear view of the entire side of the train. This can be
done through mirrors, CCTV, or a combination.

Thinking more on this since I made that comment perhaps my involvement
with underground infrastructure has confused me ... perhaps we have a
CCTV requirement that national railways do not.

IIRC, the NR platforms at Harrow-on-the-Hill only have mirrors. The
north/westbound NR platform is occasionally used by Amersham-bound LU
trains.