There was a serial killer in London during the WW2 blackouts

Gordon Cummings murdered 6 women in a style very similar to Jack the Ripper in London during the blackouts of the second world war. He was hanged for his crimes and is suspected of carrying out more which were never solved.

The only problem is - no-one seems to have heard of him. Despite the similar methods and locations as his more famous namesake 50 years earlier, news of his existence and activities comes as a urprise to many people.

When this happens, i.e. something which would be expected to be more widely known but isn't, some are pointing to a kind of Mandela Effect in reverse, where a whole set of events suddenly popped into our timeline. Research today shows they were always there, as they would be, yet no-one can remember them. 

Gordon Cummings

The Blackout Ripper was caught because he was a soldier, and left a gas mask with his army number stamped on it at the scene of one of his crimes. Ironically, he was actually executed during an air raid on June 25, 1942 at Wandsworth prison. He took advantage of the strict blackout laws that were in force during these air raids, which fined anyone heavily for even showing the slightest glimpse of light. A particularly worrying aspect of this is that people were all naturally much more trusting during this period since they were all at risk of death from the skies together. 

Cummings was in the process of murdering Greta Hayward on Valentines day, 1942 (14th February) when a delivery boy came across him and he fled, accidentally leaving behind his gas mask, which had his service number written on it. When he was arrested 2 days later, the police found his fingerprints matched those on a tin opener found at one of the crime scenes.