The Chamber Orchestra of London is a contracted session orchestra made up of professional musicians from the greater London area and beyond, brought together for recording purposes. The group's growing list of credits includes The Crown and Downton Abbey television series, two movies in the Harry Potter film franchise, and two installments of the Halo video game franchise, among many others.

The Chamber Orchestra of London (not to be confused with the London Chamber Orchestra) is a session orchestra that is flexible in how it can be constructed and where it can record, depending on the needs of the contractor. The orchestra hires principal musicians from London-area orchestras as well as international soloists and chamber musicians and is contracted by Gareth Griffiths, a former member of the BBC Symphony Orchestra and a freelance violinist. Among the Chamber Orchestra of London's first credits was the 2007 film Harry Potter and the Order of the Phoenix, returning to that franchise two years later for The Half-Blood Prince. The orchestra has also recorded with musicians outside of the scoring realm, such as George Martin, Damon Albarn, and Madonna. The group's video game credits include Halo 4, with music by Neil Davidge; Halo 5, with music by Kazuma Jinnouchi; and Battlefield 1943, with music by Ian Livingstone.

From 2010 through 2015, the Chamber Orchestra of London performed composer John Lunn's score for the hit television series Downton Abbey. The orchestra has regularly performed the film music of composers Daniel Pemberton (Steve Jobs, Enola Holmes, The Trial of the Chicago 7) and Benjamin Wallfisch (Hours, Serenity, Shazam), among others. The Chamber Orchestra of London teamed with Lunn once more in 2019 to perform the score to the first Downton Abbey film. In 2022, the orchestra took to the studio to record Martin Phipps' score for the fifth season of The Crown, and it was heard on the soundtrack to Downton Abbey: A New Era, with music once more by Lunn. ~ Keith Finke, Rovi