Cornelia Basildon-Stone

Lady Cornelia Basildon-Stone was a rich human who had many holdings around Earth but was primarily based in London in the late 19th century.

Lady Basildon-Stone was trained with "the finest fencing artists of Europe". At a diamond mine in South Africa, Lady Basildon-Stone's men had discovered a passage leading to a Silurian scientist, the last of a group who had attempted to preserve themselves. She tortured the scientist so he could explain how the genetic splicer worked before killing him.

Using the genetic splicer, a year later, Lady Basildon-Stone was implementing her plans of mutating herself into a part human, part wasp hybrid lifeform, converting London's police into her obedient "drones" and becoming the new leader of the British Empire. She did this by paying for a rainforest exhibition inside the Crystal Palace on Sydenham Hill in London. She had laid eggs in the exhibition's forest, and had all the glass in the Palace's roof replaced with glass that would turn the Palace into a greenhouse for the eggs to thrive in, and planned to make the Palace her own palace to rule from. She also made the London police go on high alert for Queen Victoria's visit, by coaxing Silas Ruckford into attempting to blow up Buckingham Palace. Ruckford was stopped by Madame Vastra, and he committed suicide before he could say who he was in league with. Later on, Lady Basildon-Stone's servant, Ajeeth, used gas piped from the genetic splicer to convert the police into human-wasp "drones" that would single-mindedly obey Lady Basildon-Stone.

Meanwhile, Vastra had climbed the Palace to investigate the Palace's exterior. Lady Basildon-Stone silently followed Vastra and snuck up on her and explained her plans, and her torture and murder of the scientist. Angered that Lady Basildon-Stone didn't know the scientist's name, Vastra drew her twin swords and took on Lady Basildon-Stone in a duel. When it seemed like Vastra was winning, Lady Basildon-Stone took on wasp form and quickly overpowered Vastra. Vastra, feeling like she was about to die, shattered the Palace roof with her sonic screwdriver and used her grappling hook to save herself from hitting the ground. Lady Basildon-Stone caught Vastra, and began to break her spine. Meanwhile, the Sontaran Strax, who had snuck into the Crystal Palace at the same time as Vastra's investigations, threw a grenade into the genetic splicer. This caused Lady Basildon-Stone to become human while she was still holding Vastra in the air. Vastra got to safety, while Lady Basildon-Stone fell to her death. Eventually, without the genetic splicer's power, the wasp genes became dormant in the "drones", and they returned to human form. The hybrid eggs had also perished. (TV: The Crystal Throne)