Dora what a magnificent tree. Some time ago John Banks of ANU came up with a formula for aging Yellow box trees based on their diameter 1.5m off the ground -try it on this tree 30-40cm = 70-94 years old 40-50 cm = 94 -117 years old 50-70cm = 117-163 years old 70-90 cm 163 -211 years old 90-120 cm 211 -280 years old 120 -150 cm 280 -351 years old
Presumably that was the circumference around the tree you measured. C=2x pi x r so that would be a diameter of 122cm which puts this tree at around 300 years old - amazing to think who and what has taken shade under it