On 04/11/2011 08:11, Roland Perry wrote:

I suppose my question is this: although there's just one Stop line, there
are arguably four separate advanced stop lines. If not four, definitely
two. Combined with the lane markings, do those constitute "separate" Stop
lines (either in the case where the is an advanced box, or in the more
general case in the absence of such a box).

Advance stop lines don't matter when there is a green light.

Or is the "One stop line" defined by the position on the traffic lights,
such that anywhere between two lights showing red is one single stop line
irrespective of paint.

Probably, but there will be some wacky layouts around.