nah, they're not a UK thing, they were released in the US years ago. I think they were released around Easter IIRC? No idea what the story behind them is, or why we suddenly got them years later (probably they're old US stock that've been dumped on us, I guess?). B&M had them for a while, not sure if they still do.
I am annoyed because the one that I don't have from the set (Lyrica..?) hasn't appeared here. All the others in multiple, but not her. Sigh. Never mind...
They didn't release Lyrica like this
only Applejack, Fluttershy, Cheerilee, Lily Blossom, Lyra, Pinkie, RD and Rarity.
Ah, just found MLPMerch's listing for these..
here.