Puzzled by Postal System

Yesterday I went to the Post Office to post off a parcel to Perth, Australia. No, no, the post mistress told me, you've missed the deadline for Christmas posting. Yes, she was talking about airmail and no, it made no difference if I sent an envelope instead of a parcel. Hmmmm. Plan B required. This morning I had a message from my son to say that the book bag and pencil case that I posted last week had arrived safely in New Zealand. I'm really glad about that, but I'm puzzled that a parcel posted last week took a week to arrive, but one posted this week is expected to take two months!

Just as well I wasn't intending to post the knitwear I've been working on.