My Sky+ box has failed after many years of faithful service. As stop-gap I have brought into use my old digibox (non recording). To my surprise, when I inserted my card into the old box, I get all the channels I previously did on my Sky+ box.
I would have expected a 'wrong card' message as I always thought the box and card had to be matched.
Why is this?
Thanks.

A Sky card will work in ANY box for all "non premium" channels (like DIscovery, Dave, MTV etc).... apart from Sky Sports and Sky Movies channels. Those two groups of channels are "premium" channels, and will only be able to be watched if the box and card are paired.
If you try to watch SSports or SMovies with the card in the wrong box then that is when you get the "wrong card" message.
This is not new, and has pretty much always been the case as far as I can remember.

In fact a SKy card with Sky+ activated will also record and playback in ANY Sky+ box without pairing - for the free channels (ie BBC, True Movies etc) at least. It has to be paired to record and playback Sky / encrypted channels.

Thanks for that, I think I've got it!
The thing is that I have just cancelled my Sky subscription (only the basic entertainment pack) but all the channels that were available on my now failed Sky+ box are there and available when the card is inserted into my spare basic Digibox. It's this total availability in the other box that I didn't expect. Thought that I would have had to call Sky to get the card and box married up for the time left until the subscription ends!
Thanks again.

A few years ago, a friend asked me to keep all my sky cards even if they were renewed. He showed me that inserting some old cards can activate all the channels even if you do not subscribe. I now keep them all now. It's a case of trial and error, but what have you go to lose?