Shrove Tuesday marks the beginning of Lent (the 40 weekdays from Ash Wednesday until Easter, the forty days and forty nights Jesus spent in the desert). Traditionally, pancakes were allowed to be made between the ringing of a curfew bell in the morning of Shrove Tuesday and its ringing again that evening.
Pancakes were made to use up all luxuries such as milk, eggs, fat and any leftovers that could not be eaten during the Lent fast and would otherwise go bad. It is also traditionally the last day of shrovetide, the English equivalent of the European Carnival tradition.
Today Shrove Tuesday is better known as Pancake Day, but we still try and give things such as chocolate and sweets up for Lent. All the more reason to enjoy Shrove Tuesday: if you're giving up your favourite nosh for Lent, enjoy it with your pancakes!