Late to the party, but that's the Dovecote Garden, also (more officially) known as the Birdcage Garden.Is the lawn that's walled off opposite woodcutters and Hex protected? Does it have a special name?
It is one of the listed garden features, so it is protected. It was once open to the public, but has been closed off since at least the 80s. Its last major usage was as the Alton Towers Zoo and later the Children's Farm.
On another topic, has anyone heard anything about how the park (and Merlin more generally) plan to handle this heat emergency?