SOLVED. Short story about boy’s magical day at the Louvre. [s]

[Rosa]

Young Parisian boy goes to the Louvre, his favorite place, with his nanny and her boyfriend, who doesn’t like the boy. Boy looks at paintings while they hold hands. Boy finds a pair of magic glasses (or maybe “spectacles”) that let him see the paintings come to life. They can see him, too. A painted lady sewing or knitting looks up, sees him, nods and smiles, and goes back to her work. The boy is filled with wonder and joy. Then his nanny’s boyfriend quite uncharacteristically offers the boy a small cake. The boy is still wearing the glasses, and he can see right through the cake to the four pills in the middle. At first he’s just puzzled, but then he realizes that the boyfriend is trying to poison him. He urges his nanny to put on the glasses, which she reluctantly does. But when she sees the pills, she starts screaming. People run over to see what’s happening, and in the hubbub, the glasses get broken.
Sometime later, after the boyfriend is presumably in prison, the boy’s mother asks him where he wants to go this weekend. I think he may have been ill for a while. He immediately answers, “The Louvre,” and she asks him if he’s sure, he’s been there so often. He answers yes, even though he knows he will never, never see the paintings alive again.
I read this kids’ short story around 2008, maybe? It felt decades older than that, though. From the 50’s through the 80’s, I’d say. I assume I read it in a collection, probably an anthology.
I’ve looked through the “Magical Paintings” list already.
Thank you!

[Ayshe]

"Potter's Grey" by Joan Aiken? It seems it was in A Goose on Your Grave and Ghostly Beasts.

[Rosa]

That has to be it. Joan Aiken was one of my very favorite authors way back--probably still is--and I actually looked at that book, too. I don't know why I didn't investigate further. Thank you so much, Ayshe! How did you find it?

[Ayshe]

You're welcome! Searching for "paintings " "spectacles" "short stories" "children's" on google books brings "Children's Literature Review" as the fifth result: A GOOSE ON YOUR GRA VE (1987) There is much variety in Joan Aiken's new collection of short stories. ... As he dons the spectacles a whole new way of seeing opens up before him. ... Time-slips, pink-tinted glasses that reveal people's thoughts and bring paintings to life, travellers from space and I thought this might be it.

[Rosa]

Inspector Ayshe closes the book on another case. I actually think I read it in this collection: Up the Chimney Down and Other Stories.