‘The Knowledge’ of London

The Knowledge

All licensed London taxi drivers need to pass a special test before they can drive one of the Capital’s famous black cabs. This test is called the Knowledge.

How long it takes to become a licensed taxi driver depends on whether you want to be an All-London driver or a Suburban driver.

London or the suburbs?

All-London drivers – also known as Green Badge drivers – need a detailed knowledge of London within a six mile radius of Charing Cross.

All-London drivers’ Knowledge is based on learning 320 routes (or runs). This will help them learn the 25,000 streets and 20,000 landmarks and places of interest in the six mile radius of Charing Cross.

It takes between two and four years to pass the All-London Knowledge. Once you are licensed you can work anywhere in the Greater London area.


Suburban drivers (also known as Yellow Badge drivers) can choose from London’s nine suburban sectors. They must know between 30 and 51 runs in detail. They also need to know all the streets, landmarks and places of interest in their sector.

It takes around two years to become a licensed Suburban taxi driver. Once qualified, you can only work in the sector you are licensed for.

You can find out more about the two licences on the T.F.L Licence types page.

The Knowledge makes your brain grow

Doing the Knowledge makes your brain bigger, says research by the Wellcome Department of Imaging Neuroscience.

Researchers scanned the brains of 16 London taxi drivers who had spent an average of two years learning the Knowledge. They found the cabbies had a larger hippocampus – an area associated with memory – than control subjects.

All information courtesy of Transport for London