I was asking a mate about this the other day who is a spark and seriously into his gadgets.

He said to me that there are things that you can buy from various places but Tesco's was mentioned(for round about £30 am sure he said ) and all you do is sit it next to the tv in another room(seperate to where your sky box is) and that it will pick up the signal from your sky box from wherever it is ion the house and that you can also change the channel via it. And it is legal,don't hold me to this cause i aint checked it yet though!