The postman just knocked on the door and handed me a board-backed envelope, and told me he hadn't wanted to put it through the letterbox because it was marked "Do not bend", so I knew it was something important.
It was my Certificate of Registration of Aircraft, issued by the Civil Aviation Authority.
It is now official. I own an aeroplane!
You'd need to know me to understand what a big deal this is for me. It is second only to my first solo and up there with losing my virginity.