As I browsed William Morris’s Printing Press (see here for the blog), I became aware of the watermark in the paper. 
It’s nothing too special, and Abbey Mills Greenfield is well known, coming from Holywell, Flintshire, the mill closing in 1982 (the Morris book is dated 1983). [For more information see, http://www.archiveswales.org.uk/anw/get_collection.php?inst_id=28&coll_id=2178&expand=]
There’s a lot to write about the history of watermarks, so this can serve to whet your appetites…
