Yes, I've looked into the situation, and from what I can glean, it was a Q&A session that JK Rowling undertook with a group of children in support of Comic Relief and the magazine reprinted the Q&A session, it did actually credit it to Comic Relief, but the problem was that we attributed it as a rare and exclusive interview with JK Rowling, which was clearly misleading, and an apology was printed.
But I think the important thing to take away from this is that we treat the word "exclusive" with respect. This situation has never recurred. We now have a process in place, you know, when we're taking interviews from another source, we make sure that we understand the circumstances in which the interview was done, and currently, had we been presented with a Q&A like this, we would now have gone to JK Rowling's representative and said, "As this was done for charity, would you be happy with us reprinting it in Hello!? If you would rather not, then we won't do it."
So the important thing that I want to make clear is that this doesn't indicate a culture and practice at the magazine. Mistakes occur occasionally, but we don't repeat the same mistakes.