"flowing away to the left under Westminster Bridge"

 

Westminster Bridge and Westminster Palace
Creative Commons Attribution Share AlikeWestminster Bridge and Westminster Palace - Credit: GraceKelly

 Westminster Bridge is a  road and foot traffic bridge over the River Thames.

Westminster Bridge, Westminster Palace and London Eye
Creative Commons Attribution Share AlikeWestminster Bridge, Westminster Palace and London Eye - Credit: ed g2s
The seven-arch, wrought-iron bridge links the Palace of Westminster on the west side of the river with County Hall and the London Eye on the east.