The Fifteenth Doctor and Ruby Sunday encountered a fairy circle in Wales in 2024. It contained a piece of paper bearing veiled references to "Mad Jack", stating "I miss you" and asking that someone "rest in peace".
In an alternate timeline, the Doctor accidentally stood on the circle, breaking it. It had mystical properties, banishing the Doctor from the world and planting a curse on Ruby that left her stalked by an old woman that would cause people to run from and avoid Ruby should they become aware of and interact with her. By 2046, Ruby was convinced that Roger ap Gwilliam was the "Mad Jack" mentioned in the fairy circle's notes, leading her to orchestrate his downfall as Prime Minister of the United Kingdom. By 2089, Ruby was sent back in time to before the Doctor stood on the circle to become the old woman, this time successfully warning her younger self, stopping the Doctor breaking the circle and thereby changing the timeline. (TV: 73 Yards [+]Russell T Davies, Doctor Who series 14 (BBC One and Disney+, 2024).)