When it’s on Kew Bridge, it would seem.
There certainly used to be a bike lane on Kew Bridge, way back when I used to cycle over it, some time around the turn of the century. They created it by drawing a nice picture of a bike and a couple of pedestrians on the pavement and letting everyone fight it out for themselves*. Then they created a bus lane and moved the bikes into the bus lane, which makes a bit more sense, given that widening the bridge isn’t really a practical option. Then they got rid of the bus lane, because it was causing such congestion even the buses complained, and went back to two lanes of traffic. But where did the bike lane go? There’s no longer a picture of a bike (but then, neither is there a picture of a pedestrian) to mark the lane any more. Nor is there a white line to separate bikes from people. All that remains of the old lane is a sign, at the other end of the bridge, saying ‘Cyclists dismount’ and a sort of race memory among the cyclists that it’s okay to cycle on the pavement.
Which means that the first most pedestrians hear of it is when they’re walking along towards the station one evening, expanding lyrically to their colleagues on their latest idea to cut global warming by having Google server farms heat entire cities, when there is a whooshing noise and a yellow lycra-clad streak tears past at speed. And only then do they remember, back in the days, that this was a bike lane once. And they’re walking in it.
* Technically, this is not a bike lane but a cop out, but we’ll let that one pass.