Thanks for your suggestion. I couldn't open the link but I'm fairly familiar with cross-referencing.

Cross-referencing is the closest I have come to getting what I want, but it doesn't work. The issue I have here is that the user would have to know to update the field so that the project number they entered appears in the header. As far as I know there is no way of making Word automatically update fields (an issue I've always had). I have set the document up so that fields are updated before printing, which could solve my problems part of the time, but it still wouldn't help for when users convert the form to pdf before printing it off.

Are there any other alternatives? I have been playing with bookmarks and think these might be the key, but until just after my original post I hadn't even known bookmarks existed, so I may need some guidance there!