This was more than a little frustrating. Getting hold of a postcard of a suitable old master painting is not an easy task. At all. I looked everywhere to no avail and then entered the world of online education resources, the stuff of nightmares. Finding and image was the easy part (but still not easy) the downloading and printing (shiny new printer) was another minefield to stumble around in. Then I happily yarn wrapped, and I lost the image reference. Noooooooooo. I may have cried at several points in the process.
For future reference dragging a jpeg onto the search bar sometimes does the trick.
I settled on this Old master mostly I had to reject images for being of very entitled Lords and Ladies or impoverished servants, or naked. Or horses.