Their knowledge is quite valuable in London (mini-cabs blindly follow the sat-nav and so will sit in traffic for longer, in my experience). Also, black cabs can

Their knowledge is quite valuable in London (mini-cabs blindly follow the sat-nav and so will sit in traffic for longer, in my experience). Also, black cabs can often make use of bus lanes (of which there are many in London) which can actually result in a quicker, cheaper journey. Perhaps the LTDA should be promoting the benefits of black cabs rather than causing a traffic jam.