London licensed taxis are called ‘black cabs‘. However, the technical regulations for the London cabs called ‘Conditions of Fitness‘ are not specifying black as the only color.
So the taxis on London streets that used to be traditionally black are allowed to be of different colors. Some traditional technical requirements stand, however. These are separate passenger and driver compartments, high internal headroom, and ability to turn 180° within the 28 ft limit.
Seen at St. Pancras International railway station drop off area (>>>), London.