It's a poppy (Papaver) on the order of this kind

https://www.bing.com/images/search?q=papaver+atlanticum+flore+pleno&form=HDRSC2&first=1&scenario=ImageBasicHover

and not a poppywort (Meconopsis). And actually not therefore a shade-loving plant.

Ah, I see you are right. Thank you very much! I was so focused on Meconopsis that I failed to look at Papaver. By the way, the ID tag was homemade as this plant came from another generous gardener. And it did well in my shady corner somehow, but now that I know its true name, I will plant more in a better, sunnier location.

Thanks again! :)