I've just realised that unbeknownst to me, my commenting system Disqus had stopped working on my blog, or was only doing a half-assed job, and I wasn't being notified of comments! It was sending me a notification of the first comment per post and then nothing else, and I hadn't been checking the blog - I've just discovered a whole pile of lovely comments left in the last 2-3 weeks! I've replied as best I can but I don't know if Disqus sends out replies to people if I do it via the website - I usually reply by email and send one directly to the commenter so I know they get it. Hopefully it's fixed, although really I have no idea what was wrong or what I did to fix it but it looks ok now.
So if you left a comment and didn't get a reply please check back on the post! I can't seem to send replies by email retrospectively.