Apparently, my own comments on my own site are now considered to be Spamworthy. I just replied to an entry and it got junked – my site back-end gave me this reason:
domain ‘davidrutt.me.uk’ found on service blue-search.net
So, either it’s having a bit of a brain-fart or my site has accidentally ended up on the list of spam-sites that Movable Type checks before approving comments. Great. Oddly enough, the previous commenter’s site also came up with the same thing, although other factors gave his comment a neutral score and it was approved.