Thanks, and just so we're talking about the same things, I've prepared a picture which not only shows the lights I'm interested in, but on the exact prototype too:
I've labelled 'A' to what I believe are marker lights, which could be white or red, although the more I look into this the more I'm convinced they are only red... Confirmation would be great.
The 'B' labels are the disc lights, obviously.
Under normal running conditions which of these sets of lights would be on on the front and rear of the loco? I understand that the built-in red lights would not have been used, and a lamp used instead.
Thanks again.