Thanks for that. In the UK, the 1st day of spring is usually on 21st March and the start of each season coincides closely with the actual dates of the equinoxes and solstices. I had to make a major re-adjustment to my thinking when I moved to Australia and discovered that the seasons began on the 1st calendar day of their respective months.
I blame mankind's constant abusive and wasting of time - the development of UT and the clock and proliferation of watches - for the change. I call it global timing.