With her mum’s permission, Mia-Rose had asked her aunt to try the Black Death sweet, which is sold by Mr Simms Olde Sweet Shoppe, a firm with more than 50 franchises in the UK and Hong Kong.

There's no true consensus that will allow us to declare an undisputed winner, but one strong candidate is a British candy called Black Death Ultra Sour, made by Mr. Simms Sweet Shop. The website ...