Well, I reversed the LCD pin order, and it didn't respond at all (not even the blocks appeared). I imagine it had to of been the correct orientation originally as otherwise the contrast adjustments wouldn't have been working.
However, believe it or not, after turning the LCD back around to its original position, "Hello world" magically appeared!!! Apart from a few missing dots in the first character (which presumably must be a hardware fault), I have a working LCD!
Thank you again for the help. I don't think I will ever know why it decided to work!