Thanks for the kind words, I'm glad this post may assist.
Interesting point about the Sigmoid derivative. Both PDL and neural networks are still new to me, so I wouldn't have caught it. I'm glad someone with more experience has had a glance over the code. I wasn't aware that it was incorrect as it's a direct port of the code from the original blog post. I just checked and that code has the same error.
Thanks for the fix.