EDIT: Haha, fastest quest ever. Two seconds after I posted this, lauren2347 messaged me: They're Charlotte Olympia brand “Mascot” shoes (link here) and GUYS, they’re on sale! (haha). I’ve edited this post to just be a fangirling squeal about them instead. Thanks, Lauren!!!
So I’ve been obsessed with Billie’s shoes since I saw her wear them after a showing of Great Britain last week. I’m not the only one, it seems: The Daily Mail is also intrigued, and the clearest shots of said shoes (the less blurry images above; the others are mine) come from them: see their hard-hitting journalistic gem “Billie Piper sports unusual tiger slippers” all about it.
Also seen here x, x (updated as more breaking news becomes available)