I've just been checking threads that I've posted to in the past, one useful one "Lesson: Webpage Design & Accessibility" - which had a link to http://www.silktide.com/ made me think that I ought to check the page for accessibility. Most of my errors were easily fixable, other than the one that I got for the search box, which said that it didn't have a label. It doesn't - fair enough.
However, I wasn't sure where to put the label, as following the instructions on WebAim, I tried in various places in the searchform.php code. (I'm using an edited Kubrick theme, but that page hasn't been edited). In general, I got the label I put in to show (which I didn't really want), however, I clearly wasn't getting it in the right place as the number of errors went up by 1 - i.e. the box still didn't have a label, and to add to that, I now had a label with no box!