Mandela Effect:
The Blackout Ripper is well known
New timeline: The Blackout Ripper is barely known
Gordon Cummings murdered 6 women in London during the blackouts of the second world war. He was hanged.
The thing is, no one has ever have heard of him?
He was a soldier, and left a gas mask with his army number stamped on it at the scene of one of his crimes.