In London's National Gallery there are, of course, plenty of pictures, but I spotted one triptych that had a picture in the middle but calligraphy on its wings. The description next to it says that it was by a Flemish painter and dated around 1485. It (the script) does look like a something between mediaeval textura and Baroque German fraktur. I have seen similar script, this time cut in stone, in a Flemish town of Bruges. It was undated (or at least I could not see any date) but this picture here gives an idea when the script was used.
There is a book available, based on this blog.
On the blog there is, so to speak, more room, one can show more illustrations there. Blogs, however, come and go, there is no certainty that it will be there ten years from now. The book, on the other hand, once you acquire it, will last, one can be sure of that.