"It is one of Leicester's most famous exports – but no-one seems quite sure who invented Blu-Tack. And as manufacturer Bostik prepares to celebrate 40 years of the sticky putty, an appeal is being made for the mastermind to step forward. The substance, made from chalk, oil and other chemicals, was a by-product of an experiment to make a new sealant. The experiment was a complete failure, but someone started using the goo to put up notices. Once the company realised what they had, they turned it blue and the rest is history." - AJCann from Bookmarklet