Well, looks like I've beaten you all to the solution on this occasion. (Although maybe it is less to do with my lightning-fast brain, than the fact that some of you are in the USA, which is at least five hours behind the UK. Basically, I just got up a bit earlier!) The answer was as follows:
My '#navigation' anchor was just outside of a table. The links that I mentioned earlier were INside the table. So, when I moved the anchor inside the top of the table as well, everything worked fine. Three further questions follow on from this:
1. Why was I putting unordered lists of links in table-cells to begin with? (Well, it was just a fast way of lining stuff up precisely, without one list disappearing under another. The finished product might use a different method entirely.)
2. Which browser was actually doing things correctly; Firefox, or the much-maligned IE? (I have no idea, but that might get you thinking if you are well acquainted with all the tech spec.)
3. What about Opera? (Dang! Forgot all about Opera. Hang on...No, Opera doesn't play ball either way round. It doesn't jump to navigation, but goes halfway down the main content area instead. Hell, I can live with that;-))
