The Knowledge of London
The Knowledge is the test every London black cab driver passes: 320 runs within six miles of Charing Cross, three to four years of study and oral exams. What it means on a taxi tour.
The Knowledge of London is the test every black cab driver passes before Transport for London licenses them: 320 set routes, called runs, inside a six-mile circle around Charing Cross, plus every street and landmark within a quarter of a mile of where each run starts and ends. TfL says mastering it typically takes three to four years. That is the quiet reason a black cab tour works. The person at the wheel spent years learning the city one street at a time before taking a single fare.
What candidates actually learn
TfL’s study guide, the Blue Book, lists the 320 runs. Each is a route between two points, and candidates learn the shortest legal way along it, then everything around both ends: streets, hotels, hospitals, theatres, police stations, clubs and monuments. TfL’s own wording is that there are “thousands of streets and landmarks” inside the six-mile radius, and it gives no single total. The figure of about 25,000 streets that guidebooks repeat is an estimate, not a TfL number.
A candidate learns them on the road, run by run, then calls them back from memory. Satnav is no help in the exam room.
How the exam works
After a written assessment, candidates sit what TfL calls appearances: one-to-one oral exams with an examiner, about 20 minutes each. A typical appearance is four questions, each asking for the shortest route between two points in London. The candidate names every street and every turn aloud, in order, and each appearance is scored from A to D. People return for appearance after appearance until the scores are good enough to move on, which is why the whole process takes years rather than months.
Green badge, yellow badge
TfL issues two kinds of taxi licence. The All London licence, the green badge, lets a driver ply for hire anywhere in Greater London. The Suburban licence, the yellow badge, covers one of nine suburban sectors. The cab tours on this site run in central London, which is green-badge country: Westminster, the City, the West End and the South Bank.
What it changes on a tour
Three things, in practice.
- Routing around the day’s closures. Central London changes week to week. From 26 October 2026 the stretch of Oxford Street between Orchard Street and Great Portland Street is closed to traffic, taxis included. A driver who knows the grid by heart takes the next street without stopping to think.
- Short hops between sights. A tour stitches together places a coach cannot reach easily, such as the lanes of the City or a mews in Mayfair, and the driver knows where a cab can pull in.
- Questions answered on the spot. Ask where the nearest good pub is, or how to walk to your hotel from the last stop, and you get a real answer.
What the Knowledge does not test is history. It is a routes and places exam. The commentary on a tour is the driver’s own, so the reviews are the place to check whether a driver is a storyteller. Some tours put a guide in the cab as well as the driver, and the listing says so.
Are tour drivers real London cabbies?
On a black cab tour the cab is a licensed London taxi, and the listings say who drives it. London City Taxi Tours says the driver-guides on its Big Sights tour are working cabbies who studied and passed the Knowledge and are also qualified tour guides. Iconic London Taxi Tours describes the guide on its electric cab tour as a Qualified Taxi Guide who completed the Knowledge. SEE MORE TAXI TOURS lists a licensed London taxi driver who is also a Blue Badge, City of London or City of Westminster registered guide on tours such as its Christmas lights tour. A private-hire car or minicab is a different licence with a different test; it can be a fine way to get around, but it is not the tour this site covers.
Where to go next
The black cab tour prices guide sets out what a cab costs per group, how many people fit in a black cab covers group sizes, and whether a cab tour is worth it weighs it against the bus and walking.
The calendar below is for the Sightseeing Black Cab Tour, the most reviewed London cab tour on GetYourGuide:
London From a Black Cab of Your Own
London Sightseeing Taxi Tours' private black cab tour collects you anywhere in central London and spends 3 to 4 hours on the landmarks, with photo stops at each and a route you can change. Rated 5.0 from 320 reviews, from US$426 for a cab of up to six as of October 2026, with free cancellation up to 24 hours before.
Check Cab Tour Dates