The Croydon Poisoning Mystery: Arsenic & the destruction of one family

Three deaths. One family. One quiet corner of South Croydon that suddenly found itself at the centre of a mystery that felt more like a Victorian thriller than the suburbs in the 1920s.

In this episode we dive into the strange chain of events that hit the Sidney and Duff families after three relatives died with the same unexplained symptoms, months apart. Doctors brushed it off, neighbours whispered, and life carried on. But once the Home Office ordered exhumations, everything changed. Each body showed clear signs of arsenic poisoning.

No intruder. No confession. No charges. Almost a century later, the Croydon Poisoning Mystery still sits in a very uncomfortable grey area.

We walk through the family tensions, the red flags and the unanswered questions — all sprinkled with our usual chaos, including the saga of the noise-cancelling headphones that turned Morrisons into sensory deprivation, whether stroking someone’s arm is science or just creepy, a full rant about eight-year-olds with teenage attitudes, and the ongoing diplomatic crisis caused by that comment about cheap suits.

Sources include:

https://beardyhistory.com/2025/08/10/unsolved-arsenic-murders-in-croydon
https://trove.nla.gov.au/newspaper/article/53486769#:~:text=,Croydon%20%28England
https://www.insidehook.com/adventure/hidden-venom-famous-unsolved-poisonings
https://beardyhistory.com/2025/08/10/unsolved-arsenic-murders-in-croydon
https://insidecroydon.com/2022/01/08/did-the-south-croydon-poisoner-really-get-away-with-murder/
https://historywiki.therai.org.uk/index.php?title=Edmund_Creighton_Duff
https://www.everand.com/book/897323633/Poisonous-Lies-The-Croydon-Arsenic-Mystery-Great-Unsolved-Murders-of-the-20th-Century
https://forum.casebook.org/forum/social-chat/other-mysteries/6176-the-croydon-poisonings

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Produced and hosted by Hannah Williams & Rachel Baines
Mixed & edited by Purple Waves Sound (A.K.A Will)