Claudius is quite frank here about the loveless and sexless state of his marriage, and the fact that his relationship with Acte, a prostitute, was "a purely business one." She and her successor in this role, Calpurnia, become very significant characters later on.
Acte is a fictional character, but Tacitus tells us of two "mistresses" to whose company the historical Claudius was "especially partial," one of whom was named Calpurnia.
The historical Claudius, in contrast to Tiberius, Caligula and Nero, seems to have been exclusively heterosexual. Suetonius tells us that "his passions for women were most ardent but he had no relations at all with males."
Marcus Vipsanius Agrippa Postumus (12 BC - 14 AD) was the son of Marcus Vipsanius Agrippa and the disgraced Julia Augusti Filia. He was therefore Augustus's grandson. Tacitus tells us that he was banished, but the reason for his exile is unclear. Tacitus hints at an antipathy between Postumus and Livia, and this is the theme that Graves picks up on. Graves's fictionalised account is an attempt to explain what history has failed to elucidate.