Camulodunum Camulodunum Camulodunum (; ), the Ancient Roman name for what is now Colchester in Essex, was an important town in Roman Britain, and the first capital of the province. It is claimed to be the oldest town in Britain. Originally the site of the Brythonic-Celtic oppidum of Camulodunon (meaning "stronghold of Camulos"), capital of the Trinovantes and later the Catuvellauni tribes, it was first mentioned by name on coinage minted by the chieftain Tasciovanus sometime between 20 and 10 BC. The Roman town began life as a Roman Legionary base constructed in the AD 40s on the site of the
A Town Called Mercy called the Gunslinger. However, the Gunslinger is a product of experiments by Jex to win a civil war on his planet, and the Doctor is unsure of what is the right thing to do. Showrunner Steven Moffat pitched the Wild West theme to Whithouse when thinking of ways to give each episode a distinct theme. Whithouse further developed the theme, including classic Western tropes and a sympathetic villain. "A Town Called Mercy" and the previous episode "Dinosaurs on a Spaceship" were the first to enter production for the seventh series. Much of the episode was filmed in March 2012 in