Charnwood Noon Column

Today was a better day, hardly a splash of rain, a result in the kitchen reconstruction project, and a pleasant walk with No 2 son and his dog this evening.
Waked past this tree trunk that has a slot which the sun shines through at noon on the winter and summer solstice, not exactly noon actually 3 minutes past according to the information plate - anyone like to suggest why that is?
Anyway it looked interesting, scientific and natural at the same time, I like that.
I understand that this has been Blipped before, also that there are six others spread across the midlands.