While the changes affect all of London's private hire firms, Uber has been very vocal in its opposition. TfL originally mooted the idea of capping the number of private hire vehicles and enforcing a Knowledge-like test (like drivers of London's iconic black cabs must pass) to improve driver understanding of the city, but those plans were scrapped in favour of an English language test and a push for better customer support and vehicle insurance.

Uber took the English requirement to the High Court, arguing that a test would reduce the number of drivers on the road, ramp up prices and was in some ways more difficult than the exam required to gain British citizenship.

It wasn't able to block its introduction, but Uber was able to convince the court that asking drivers from predominantly non-English speaking countries for proof was discriminatory. This means that London's 110,000 private hire drivers will one day need to supply the necessary documentation regardless of their nationality.

British drivers will be able to use an A-G GSCE qualification as proof, but non-English drivers need to pass a test that meets European Common European Framework of Reference (CEFR) guidelines. The B1 exam is said to be on par with tests taken by nine and 11-year-old secondary school pupils.

"It is essential for public safety that all licensed drivers can communicate in English at an appropriate level. Drivers must be able to communicate with passengers to discuss a route, or fare, as well as reading and understanding important regulatory, safety and travel information," says Helen Chapman, TfL's General Manager for Taxi and Private Hire. "We are clear that this is crucial to a driver's role in transporting the public."

To ease fears of a driver shortage, TfL says that any driver applying after the October 14th deadline have until March 31st, 2017 to prove their English skills. Those who have already got a TfL licence only need to supply documentation when they come to renew their accreditation, which must be done every three years. It also means TfL won't have to sift through 110,000 English language certifications all at once.

Uber, which recently cried foul over London Mayor Sadiq Khan's plan to boost London's black cab trade, believes a written English exam is unnecessary:

"It's disappointing that, to try and dig themselves out of a legal hole, TfL is now insisting every private hire driver in London must have essay writing skills. We've always supported spoken English skills, but passing a written English exam has nothing to do with communicating with passengers or getting them safely from A to B."

"Thousands of drivers who've spent years providing a great service to Londoners will now have to fork out £200 and pass a writing exam, try to find an old GCSE certificate or lose their licence and their livelihood. Transport for London should think again and scrap these unnecessary new rules."