I actually had to catch a cab from Earl's Court to Kew Gardens because District Line had issues. I got in and told the driver, an elderly man, my destination of Victoria Gate, Kew Gardens. First red flag, he wasn't sure where that was. Second red flag, he pulls out a paper map book, like the kind I haven't seen for 10 years. Third red flag he doesn't even know which lane to exit the roundabout to go towards Kew.
I proceeded to watch on my smartphone how he went completely the wrong way and added 20 minutes to the trip getting stuck in heavy traffic. I'm well familiar with The Knowledge, and I can tell you without a doubt, someone lent this old codger his black cab. Whatever idiot cabbie did that did far more damage to the cause of the traditional black cabs than anything Uber could ever do.