John Rowland wrote:

There are numerous places in Greater London where traffic lights give
buses (usually taxis too) priority over other traffic. They generally
take the form of a traffic light on a short island between the bus
lane and the traffic lanes(s), with no stop line in the bus lane, and
they occur just before a traffic light controlled junction and are
synchronised with it. For most of the time that the main traffic
lights are red, only bus lane traffic can get to the main junction,
then when the main junction is about to turn green, all traffic is
allowed to reach the main lights. So conceptually it's the same as
advanced stop lines for cycles.

Actually, I've just realised what a clever device these are. They give the
bus the equivalent of a bus lane right up to the lights, but with the added
ability to potentially turn right, while they don't reduce the capacity of
the junction for other traffic one iota in the way a bus lane right up to
the lights would.

Here's one in Seven Sisters Road on the northbound approach to
Fonthill Rd...
http://maps.live.com/default.aspx?v=...cl=1&encType=1

Here's one in South Lambeth Road just before you hit the Vauxhall one
way system.
http://maps.live.com/default.aspx?v=...cl=1&encType=1

Here's one in Harrow....
http://maps.live.com/default.aspx?v=...cl=1&encType=1

Here's one near the Ironbridge in Hanwell/Southall
http://maps.live.com/default.aspx?v=...cl=1&encType=1

This looks like another version even closer to the Ironbridge,
although I've never noticed this one on the ground, I found it now
when I was looking for a map of the other.
http://maps.live.com/default.aspx?v=...cl=1&encType=1

I think there are some in Walworth Rd and Camberwell Road, but they
might be too new to be on the photos. This is nowhere near an
exhaustive list.