They are all over London and all sorts of different shapes. Some are there to protect pedestrians, buildings and corners; others have dual purpose as boundary markers.
My 'collection' is quite pathetic compared to Maggie's set... she's bollard mad!
Top: Caledonian Rd, Bow Common Lane, Hoxton, Acton.
Middle: Carter Lane, Lambs Conduit St, Leytonstone, Holland Park.
Bottom: Camden, Middlesex St, Highgate, Upper St.