The tip was on the interview Nicola did on BBC news that was linked a few days ago. I'm unsure if the link will work or is available any more as the news episode is no longer on iplayer.
They asked about the reasoning behind having family run phone lines and Nicola said about how they could answer the phones 24/7 as police lines shut at 5pm due to resources and used the example that a woman called anonymously with a significant tip but had said she didn't want to talk to police, she was aware Nicola would (and has) passed it in to police.