No, the unexpected parcel was the one with mkillingworth's return address on. Now, writing an address on a large padded envelope is a fairly deliberate thing to do, and it wasn't going to be an accident. But for the life of me, I couldn't work out what she would have wanted to send to me.
If in doubt, open it.
The parcel was actually on behalf of Jane and Scott Dennis, owners of Fo'paws, from whom I'd ordered 3 Nippon 3007 polo shirts back at Eastercon. Because of shipping costs from the US, we'd agreed that the shirts needn't be posted from Kentucky, and their next visit over here in June was soon enough.
So, Marcia, received. Thank you.