Firstly this one posted in Sydney in 1932 with a George V penny stamp and slogan postmark.
I thought the 'POSTED IN PILLAR BOX' cancellation interesting, I'm not sure why that would have been noteworthy, maybe at the time most letters were posted at a Post Office, and they wanted to promote pillar boxes, but I really don't know the reason. A bit of googling and it seems there was a series of these Pillarbox slogans, some of which are listed in this thread.
Then on to the postcard from New Zealand.
I hope no one was hurt and that no one was too disappointed.
You can read a little bit about it here - scroll down to 1965 October 16.
This post is part of Viridian's Sunday Stamps, you can check out this week's entries by clicking on the icon below.