~20 years ago we were on vacation in Zeeuws Vlanderen. It was e x t r e m e l y boring. (Sorry, Zeuws Vlanderen). So we decided to hop over the channel to visit England. Our kids were too young to have their own ID cards, and as citizens of Schengenland we were not prepared for the UK border control. Of course nobody on the French side cared to tell anyone about British immigration rules. So we were at the border control in Dover without IDs for our kids. They accepted their health insurance cards, and we spent a wonderful week in Kent and London, even meeting a veteran from the battle of Arnhem. Luckily they let us leave as well – it occured to me only years later that leaving might have become a problem.