This is the original vintage cover painting for book #5  in "The Lymond Chronicles"  Series by Dorothy Dunnett, published by Sphere 1976.  "Combining all the political intrigue of Game of Thrones with the sweeping romanticism of Outlander" is the description for these books,  and yet written decades earlier!  Pether excelled in romantic historical fiction and produced dozens of cover paintings in that genre for major publishers of the time.   This one hand-painted in gouache and acrylic on illustration board, and is the typical British size for book cover illustrations ("flats") of the day. at 15.75" x 8.5" and comes with a label attesting to its authenticity signed by Pether's widow, mounted to the back.  Interestingly Pether did another cover - similar - for the Sphere edition in 1974!  Vintage art like this is getting hard to find,  so if you want this one, don't hesitate!