Licence badge; brass badge as issued to London taxi cab driver 59668, circa 1995

All London taxi cab drivers must hold a current licence. The licensing process is regulated by the Public Carriage Office (PCO). A licence badge, such as this one, must be on display whenever the driver is on duty. For a driver to be licensed by the PCO, he or she must be medically fit, trustworthy and financially solvent. This is particularly important for owner-drivers who are responsible for maintaining their own cabs. Drivers also have to 'do the knowledge', memorising and being tested on about 468 set routes around London's complex street system.