Cars (esp. cabs, but they make up a fair proportion of the traffic here) seem to use the left hand filter lane to undertake me going east on the Westminster bridge approach (pic attached) quite a lot. They usually swerve back in to the lane I'm in before the island/bollards and go across the bridge, which means I have to brake hard to avoid them . I usually take the lane here (primary) and I'm not going particularly slowly, so any advice on positioning, etc. from the experts to make this less likely please?