From Kate Middleton to Avril Lavigne — here's why conspiracy theories are never 'harmless'

“It’s exciting. It feels like a movie where you can take the role of detective and you fill in the blanks. It’s very emotive in that way.”

Kate Middleton recording her message announcing that following her abdominal surgery in January "tests after the operation found cancer had been present." Pic: BBC Studios/PA Wire

Since March 10, the hashtags #whereiskate, #katebodydouble, and #katemiddleton have reached more than 400m people, according to media monitoring and analysis company, BrandMentions. I am one of those.

In a matter of weeks, the alleged ‘disappearance’ of Kate Middleton snowballed from a niche interest to a social media frenzy.