I love the expertise here on this forum on the cars from the movies and I always see the license plates (registration) on the English cars deciphered using the UK database tools. Do we know as standard practice that the UK film industry actually used real license plate numbers? I'm mainly referring to movies with 1960s English cars. In the U.S. the art rooms make up a plate number. Thanks

Often cars keep their real original plates indeed.
But that's also the case in the US in recent movies: we often had cases of valid plates, from which we can have info.