Many years ago I had the roof on my rear addition replaced as some of the tiles were broken, and not possible to get replacements easily. So I kept the old good ones as spares for the main roof. Which was also replaced ages ago. ;-)
Think they are called double pan tiles. They are about 2' x 2' Have two curved ridges in them.
Having a de-clutter of the cellar, and wondered if they have any value, or just take them to the tip?