Bertie Potts created his own clone in order to test River Song. The clone's task was to bring River to a Surene tomb in Lower Mesopotamia, contaminated with saline drones. To observe how River solves the mystery and fights the artificially created an undead monster inside the tomb, the real Bertie hacked his clone's senses.
To fulfill his task, the clone worked in the British consulate in Ur, near the contaminated tomb. He was skinny and wore a three-piece suit even in the desert. He claimed to remember being sent to a prep school at the age of five and not having friendly human contact for the next twelve years. He could vividly remember his nanny who took him to the prep school.
After the tomb was discovered in 1924, the clone made sure to "accidentally" meet River on a steamer from Southampton to Constantinople. He then provided her with a car to get to the tomb and followed her into the tomb. In the rush of the fight with undead Prim, he let slip his knowledge that River owned a vortex manipulator. Shortly thereafter he came in contact with Daphne Garsington, already contaminated with saline drones, and, consequently, became infected himself. River was forced to leave him in the tomb, unable to help, but before she left he said that the history of this tribe was manipulated to test her. He gave River a letter containing an invitation.
Feeling the saline-drone induced thirst, he let Prim out of the inner chamber. His cries as she was devouring him could be heard outside the tomb. (AUDIO: The Boundless Sea, The Rulers of the Universe)