Which is correct:
- Scarcely did she put down the phone when it rang again.
- Scarcely had she put down the phone when it rang again.
My own take is that both are correct, but that "had she" indicates a connection between the phone ringing and the fact that it was put down.
My "adversary" believes that only "had she" (past perfect) is correct, because the putting down precedes a past event, ie the phone ringing.