In message , at
23:45:56 on Thu, 3 Nov 2011, Nick Finnigan remarked:
You could argue that you're not forced to use the lanes for any given
direction. So long as a leftwards arrow is lit and you drive with
appropriate care, you can turn left from any lane.

Even if that means passing a red light (because the middle lane in
question
isn't yet showing a "straight ahead" green arrow)?

Yes, provided the lanes are just white lines, not kerbs.

The one I'm thinking of has a small traffic island, but you could turn left
past it; in other words you are saying the silver hatchback here could
immediately turn left (despite being in the wrong lane and facing a red
light): http://tinyurl.com/6kkff8b

No, because there are separate stop lines for the two sets of lights.

Does it require a physical barrier like the traffic island to create
*separate* stop lines - or could paint achieve it as well?

Dunno, I'd need to see an example.

I'm thinking of junctions like Cross Street (A56) and Dane Road in Sale.
4 1/2 lanes, markings for left, ahead, ahead, right but only one stop
line (+two 'advance' stop lines), no kerbs / separate slip roads.
However, two complete sets of lights to allow turning on a filter, from
any lane.

OK, so in that case you are saying it's legal to (say) turn left from
the "straight ahead" lanes, because the lane markings are perhaps only
advisory and you are crossing the same "Stop" line whichever lane you
are in. With a filter-left you have to cross the Stop line, and that it
doesn't matter which part of the stop line.

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).

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.
--
Roland Perry