On the London transport website there is a warning about using unlicensed mini-cabs. It says they are not allowed to stop and pick up people who hail them on the street ( only licensed black cabs can do that) but sometimes they do anyway.
How do we make sure the cab we hail is a licensed black cab? Apparently they can be covered by ads so not recognizable by the black color anymore. We will be four women traveling together and want to get it right.