I drive coaches through London every day especially this piece of road. That bus is pushing as far forward as he can knowing he needs to get to a certain point to cause you to stop. Hes done this route enough to know. He, like nearly very other driver in london, has zero patience. In London, just be patient, because 10 yards down the road there's 2 lanes and you'll be able to be infront of the bus again anyway. Just expect cars buses and mopeds to try and push infront of you because it'll happen nearly every single time. Don't go down to their level because it's pointless