BLACK cabs are an emblem of central London’s streets, but an estimated 30 per cent of the 25,000 people who drive them actually live in Essex.

One of the largest firms specialising in the sales, service and repair of London cabs is Just Taxis, in Benfleet. In 2009, its owner, Robert Webb, also set up a training school for black cab drivers, based in Grays, called Just-Knowledge.

Here Robert, along with his colleague John Sultana, a full-time cab driver they teach “the Knowledge”. This is the term given to the black cabbie’s comprehensive grasp of every London street and alleyway.

Robert says: “Black cab drivers are known as the best qualified in any city in the world. It’s amazing what those guys are expected to carry around in their heads.”

Apart from the distinctive cabs themselves, the Knowledge is the main feature that distinguishes London’s black cab drivers from others who ferry passengers for a living. It isn’t called the Knowledge (must be capped up)for nothing.

Black cab drivers are expected to have instant recall of 25,000 streets, as well as knowing the location of thousands of sites ranging from hospitals and tube stations to pubs and restaurants, along with random information such as the order of theatre names in Shaftesbury Avenue.

The drop-out rate of those embarking on the Knowledge is around 70 per cent. The average length of time taken to acquire it is four years.

“But there are big variations,” says Robert. “Some guys manage to pick it up in six months.”

As they proceed with the Knowledge, the wannabes undergo regular tests with an examiner, known as “appearances”. Learner cabbies do not need to go to a Knowledge college. John says they can study at home.

The majority study with other trainees. Full-time black cabbies can earn about £35,000 a year.

Black cabbies remain self-employed operators, and many own their own cabs. Alternatively, they can work for one of the large companies based in London.

The trade is overseen by Transport for London. Full details of the requirements, along with an application form, are available from