If you thought your nan was the only one hiding her money in empty coffee tins, then you were wrong — as it turns out, even the royals use this simple trick to protect their precious items. According to a BBC documentary about the Queen's coronation [1], some of the gems from the Crown Jewels [2] (including the Black Prince's Ruby) were actually hidden in a biscuit tin, which was then buried in a secret exit in Windsor Castle [3] during World War II. Fearful of a Nazi invasion, officials took the precious stones to the castle and hid them in a deep hole following orders from King George VI, the Queen's father [4].
So, next time your nan tells you to hide your jewellery before you go on holiday, don't just roll your eyes — do it!