The heart next to it is the centre of the Ace of Hearts of a regular Waddington's Number 1 pack. Yes, this new pack is tiny — I believe it was manufactured for dollhouses. It's hard to find out much about it, though, because it doesn't appear in any of the usual catalogues. I guess the fact that it's so small means they don't count it as being a pack of cards (you'd have a hard job playing a game with it). The cards are turned, so it probably dates from around 1870 or so.
These things show up every 3 months or so on eBay, but I've never won a bid before because they usually go for five times more than I'm willing to pay. This time I struck lucky, perhaps because they were sold from the Netherlands so American collectors didn't see them.
Now I have to figure out how to get them back in the box...