Who ruled Britain in 40AD?

In 40 AD, Britain was not yet fully under Roman control, but the region was influenced by the Roman Empire. At this time, the Roman Emperor was Caligula, who ruled from 37 to 41 AD. The native tribes in Britain were led by various local chieftains, and the Romans had not yet launched a full-scale invasion, which would occur later in 43 AD under Emperor Claudius.