The copyright for a photo taken by a monkey belongs to no one, as animals cannot own copyrights. According to the UK Copyright, Designs and Patents Act 1988, the author of a work is the person who creates it, and a monkey is not considered a person under UK law. Therefore, the photo taken by the monkey is in the public domain, and anyone can use it without infringing on any copyright.
This conclusion is based on the ruling in the case of Naruto, a crested black macaque, who took a selfie with a camera owned by wildlife photographer David Slater. The case was settled out of court, with Slater agreeing to donate a portion of future revenues from the photographs to wildlife organizations. However, the court of appeals declined to dismiss the appeal and vacate the lower court judgment, stating that animals cannot own copyrights.
In summary, since a monkey cannot be considered the author of a work under UK law, the copyright for a photo taken by a monkey belongs to no one, and it is in the public domain.