Yes and even if stationary take care. This morning I chose to wait behind a white van that was behind a nasty truck waiting to go through the Queenstown Road roundabout but 2 cyclists undertook both vehicles they went ok but obviously as they couldn't seen what was happening on the roundabout they couldn't know when the truck was going to turn (and where it was going).
Let them see you.

and yesterday I saw a female cyclist almost taken out at the Clapham Common/Cedars Road junction as she was too important to wait at the traffic lights.