The London Hackney Cab.

London's Hackney Cabs have always been identifiable by their shape and the fact that they have plates on the back and inside the vehicle with a number on it. Plus the driver wears a badge displayed on his/her chest displaying a different number.
The driver is identifiable and the Taxi is identifiable by the licensing authority. That's how it has always been.

Private Hire, Provincial.

Private hire vehicles in the provinces have always had similar plates to London Taxi's, that state that the vehicle is private hire.
The Plate carries a number by which the vehicle is identifiable and comes in a variety of different colours, depending on the licensing authorities preference.

Private Hire In London.

Why has TFL seen fit to issue London's private hire vehicles with paper stickers that are placed on windows, most of which are tinted, which make the license roundel illegible.
Why are they not carrying proper plates on the front and back similar to the provincial private hire vehicles.

Or should we lose the numbers. After all, we are not numbers we are all free men!

http://theandersonshelter.blogspot.com/2008/10/why-do-londons-mini-cabs-have-silly.html