Not sure what you are talking about. What music in particular? Most music for film is recorded specifically for the film. The bulk of it in London UK.
The UK is now producing a huge part of movie productions especially the music. A lot, if not most of Hollywood's engineering production and now filming takes place in the UK. There are now large movie studios in Kent in particular, especially around Ashford, and now in the old Chatham naval dockyard.
In terms of music, London has two orchestras that do a lot of work for the movies.
The London Film Music Orchestra is specifically for film production. The
Sinfonia of London, is one of the five major London Symphony Orchestras. As well has a regular concert series, including at the Proms since 2022, they also specialize in music for movies. The conductor and owner is John Wilson.
In addition to that, musical recording and production standards, are extremely high in the UK. There are university entities with advanced programs offering degrees in musical production via Tonmeister programs.
The BBC continues to set a high bar and standard in audio and AV productions. The last night of the 2024 Proms was Saturday. The Royal Albert Hall was packed with 6,500 people night after night for 72 concerts over the last two months. I don't know of any other city in the world were anything like that would be possible.
There are also major symphony orchestras in each of the devolved nations of the UK and in major center like Birmingham and Manchester, that latter being the home of the Halle Orchestra.
All of this explains why much of the music associated with films is produced to such a high standard. It is not by chance.
