Just plug and play, but you will need to pair the sky card from the Sky+ box with your new HD box

Thanks for the info and excuse my ignorance but what does "pair" mean and how do I do it?

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“There is no more lovely country than Monmouthshire in early spring. Nowhere do the larks sing quite so passionately, as if somehow inspired by the Welsh themselves. There is a blackbird on every thorn and a cock chaffinch, a twink as they call him there, on every bush...... It moved me profoundly. I had been spared to see another spring, and I thank God for it.”

Oliver Kite
“A Spring Day on the Usk”
A Fisherman’s Diary

Your Sky viewing card is linked to the Sky box it is inserted too, if you simply plug it into another box it won't work as the box will not recognise it, so the the two have to be configured (paired)

OK I get that but how do I do it? Is it a case of calling Sky or is there a process that I can carry out?

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“There is no more lovely country than Monmouthshire in early spring. Nowhere do the larks sing quite so passionately, as if somehow inspired by the Welsh themselves. There is a blackbird on every thorn and a cock chaffinch, a twink as they call him there, on every bush...... It moved me profoundly. I had been spared to see another spring, and I thank God for it.”

Oliver Kite
“A Spring Day on the Usk”
A Fisherman’s Diary

I have had three replacement boxes since I have been with sky, the engineer that came to fit them had to phone sky to pair the card with the box.

You would also have to subscribe to get the HD channels at £10 a month.