A human empire fought the Cybermen in the far future. The empire was ruled by an emperor of the Imperial family. Its currency came in the form of coins including the Imperial shilling and the Imperial penny. These coins featured the image of the emperor. The empire included an Imperial Court and Proconsul. (TV: Nightmare in Silver)
As Porridge explained to Clara Oswald, humanity faced the Cybermen of the Cyberiad in the Cyber-Wars. These Cyber-Wars had the Cybermen constantly upgrading themselves to overcome any weaknesses that could be exploited. Ultimately, the conflict was only ended when a bomb was deployed which completely destroyed Tiberian spiral galaxy and seemingly all of the Cybermen with it. At the time of its destruction, the Tiberian spiral galaxy contained a million star systems, a hundred million worlds and a billion trillion people.
Because of the damage done to one of the planets the war was fought on, Hedgewick bought it cheap and set up his own amusement park there; it was said to be the best ever in all of history. However, unknown to all, the planet had become home to three million damaged Cybermen transported there by a Valkyrie during the war. Patrons from Hedgewick's World of Wonders began to be kidnapped to supply spare parts to fix the damaged Cybermen.
Some of the deactivated Cyber-suits also ended up in Webley's collection. However, they had similar appearances to the variety of Cybermen created by Cybus Industries and those of the Cyber Legions. (TV: Nightmare in Silver)
A thousand years following the defeat of the Cybermen, the empire was ruled by Emperor Ludens Nimrod Kendrick Cord Longstaff XLI, also known as "Porridge". He succeeded the old Emperor, whom he had accompanied when he, protected by the Imperial Guard, attended the ice picnic on Caspertine, where the snow bears danced for them. Alice Ferrin was a member of the Imperial Guard, whom mostly attended parades. (TV: Nightmare in Silver)
"Porridge" was represented on the coins of the empire. Being, in the words of Angie Maitland, a "little bloke," he was made to appear much taller in his statues. Feeling the pressures of his office, "Porridge" left his title behind and escaped to Hedgewick's World of Wonders, where he became friends with Webley.
When the Eleventh Doctor, Clara Oswald, Angie Maitland and Artie Maitland visited the World of Wonders, he controlled a Cyberman when Artie was playing chess with it. Clara was put in charge of the platoon when the real Cybermen attacked. He helped her commanding the military staff. Later, when the Cybermen were temporally deactivated, Angie revealed that she had guessed his identity soon after meeting him. Conceding that the ending the threat of the Cybermen was more important than escaping his duties, Porridge activated the bomb that would implode the planet. The activation summoned the Imperial Flagship which transmatted everyone aboard moments later. The Cybermen and the planet were destroyed, and Porridge's ship was now a safe distance from the danger. In the ship, he proposed to Clara, telling her that he had "never met someone" like her, and that she could be "the queen of a thousand galaxies, and the wife of the emperor". Clara refused, telling him that she did not want to be a queen. Porridge then jokingly ordered Clara and her three friends to be executed, then told them to go before he changed his mind.
Once everyone else was gone, Porridge had the Imperial Flagship scan the debris for signs of surviving Cybermen, but detected none. Porridge briefly joked with Gloria about his job before having his ship take him home. (TV: Nightmare in Silver)
Behind the scenes
Though not stated in the episode, writer Neil Gaiman revealed that he set Nightmare in Silver as taking place "a quarter of a million years into the future." This would place the empire beyond the timeframe of the Fourth Great and Bountiful Human Empire, dated by the Ninth Doctor to the year 200,000 in The Long Game.