This binding was invented by Carmencho Arregui, a Spanish bookbinder and conservator. It is based on the traditional long stitch binding. Her goal was to allow access to the spine but still protect the text block and to offer protection without adhesives. The idea being that over time the paper/parchment along the spine of a book would need reinforcing, and this cover allows that to happen without removing the sewing. Her marvellous website is here:
This binding has been widely embraced by non-conservators for its decorative possibilities and suits a large variety of cover materials - paper, vinyl and leather all work perfectly.
A video tour is below - the books open perfectly flat which is great for a sketch book.