Apologise for the feed interruption
While make some changes to the front page (I finally found a way to include the content I wanted!) I accidentally copied the settings file from my ‘dev’ directory to my actual website directory. The dev version only has a placeholder URL and site name in the settings.
Now I've gotten a reminder where I use those settings.
In addition to the header, the feeds rely on these. When I regenerated the site with the placeholder values in the settings file, every old post in the feeds were given a new URL and unique ID. This would result in your feed reader thinking these old posts were new posts. And a dead link to these posts.
Will try not to do that again! ^_^