Produced at Carbodies' Holyhead Road plant from 1958-1997. Strange how everyone else in the world thinks of this as being a "London" taxi. One author I know even refused to believe it was used in any city other than London! I actually prefer the previous FX3 with it's half-cab design and which continued in service for some years after the FX4 was introduced.
Here's a useless piece of trivia which I learned only recently. If you look very carefully you will see it's the same old FX4 cab with the same driver (Jonathan Stratt) in almost every TV and movie production! He is a real taxi driver (as well as being an actor) who owns his own cab and is highly regarded in the showbusiness world as being a reliable extra.