The "Silver Lady" was a name given by Charles Babbage to a figurine, that could summon the Kasaavin.

It was built by the Spy Master for the "tranmission and conversion". It could transmit the Kasaavin energy around the world all at once into every device hitting every human being and erase all their DNA simultaneously.

By 1834, it was gifted to Charles Babbge, delivered by a young man, who said it was a "token of appreciation from his master". According to Charles Babbage it was "a revolutionary piece of engineering", though he thought it to be as much for decoration as for purpose, "like all great ladies". He told the Thirteenth Doctor that it moves and, on occasion, projects. These "projections" turned out to be the Kasaavin. The Doctor came into conclusion, that this machine is used to stabilise the Kasaavin in this world. The Doctor used her sonic screwdriver on the "Silver Lady" to summon a Kasaavin so that it would bring her back to the 21st century. Before the Doctor touched the Kasaavin, Ada grabbed her hand, and they both were brought to Paris in 1943.

In the middle of 2019, using the Spy Master's TARDIS which she had stolen in 1943, the Doctor built in a computer virus as a fail-safe into the Silver Lady after tracing its movement throughout history.

By 2020, the figurine was placed in Daniel Barton's office at VOR. It summoned several Kasaavin beings, one of which captured Yasmin Khan and transported her into the Kasaavin realm. Later it was moved to Essex, where the Master's plan was prevented by the Thirteenth Doctor thanks to the fail-safe that she had retroactively placed into the figurine. (TV: Spyfall ^[+]Chris Chibnall, Doctor Who series 12 (BBC One, 2020).)