A Sky card will work in ANY Sky box.

However, the Sky card would need to be 'paired' to the Spanish Sky box to recieive the Sky Sports and Sky Movies channels. Otherwise if you try to watch these channels you will get a "This is the wrong card for this set top box" on screen message.

However all the other channels, like Sky On, Dave, Sky Sports News, will work in any box without pairing.

That said what channels you can receive will depend on your location and installation (dish size, etc).