Spyke wrote in message ...
In message , J. Public
writes
Hi All.

Just a quick question - does anyone know what a small illuminated 'J' might
be used for on the northbound met platform at Finchley Road station. It
looks a bit like that light that goes on then off as the train passes over
the little arm at the side of the track.

I'm guessing it's probably an indicator to inform a Met driver and/or
the station staff that a Jubilee line train is approaching, and that it
might be a good idea to let the Met train wait to allow passengers to
from the Jubilee line to transfer to it.

Indeed it is, it illuminates when the platform track circuit is
occupied. There are also M indicators on the jubilee line side.
However, the drivers never seem to wait and allow passengers to
change.