Upon browsing some of the back-up files for the articles on this site, I suffered the horrifying revelation that my old essays are riddled with typos. These cannot have been present in my original handwritten work or the markers would surely have noticed them. I assume therefore that they came about in 2015-16 when I was typing them up on an old laptop with a slightly stiff keypad. I have now gone through all my old posts correcting as many errors as I could spot. Hopefully anyone using my work as a source for theirs has corrected the errors before submission.