(They were first produced in Sheffield, England, by Geo. Bassett & Co Ltd, under the name Bassett's Allsorts, but the idea of mixing up several sweets came about by accident. According to Basset's own marketing, in 1899 a sales representative for the company, Charlie Thompson, supposedly dropped a tray of samples he was showing a client in Leicester, mixing up the various sweets. After he scrambled to re-arrange them, the client was intrigued by the new creation.
All I know is they are delicious, and thankfully there isn't one bit of salted liquorice in them.)