The Artists Partnership is a Spotlight registered agency located in Soho (W1B 5NE).
The agency represents adults for work as actors, writers, and voice over artists. Clients can choose to be represented only for voice over and commercial work.
They have a busy Twitter feed @TheAPartnership.
Annalisa Gordon from The Artists Partnership has a Q&A with Spotlight which gives useful insight into how to approach an agent.
Carefully read the FAQ page for instructions about applying, because they are different according to your chosen area of work.
An elite agency, your application is most likely to succeed when you’ve won industry awards or are stopped in the street by fans. This is not an agency for unknown beginners.