If I recall correctly, there was another thread related to this. The poster was having a lot of trouble getting any credit established, and was told it was because she wasn't on the electoral roll, even though she wasn't eligible to vote. As it turned out, the problem was that her address wasn't on the roll; it was a new building, and no one had registered from that address previously. The reason it mattered was that companies used the electoral roll as a way to verify that an address was a valid residence.
So, if all that is correct, then it would seem that, as long as someone has registered from your address (which seems pretty likely, if you're living with a UKC partner/family member/flatmate, or if it's an old enough building), you're probably ok.
Of course, there may be more to it.