Shortbread biscuits go back as far as the twelfth century, but at that point were much more bread-like because they used leavening agents. It was not until the the leavening agents were replaced with butter that they became the popular crumbly treat that they are today.
Although there are not many things I would like to say that I have in common with Mary Queen of Scots, her love of shortbread biscuits is one of them. It is in fact rumoured that she is responsible for the name petticoat tails. Unlike the most commonly finger finger shaped shorbread, petticoat tails are named as such because they resemble the shape of women's petticoats. Based on the brands I used, each biscuit is about 94 calories.