Use these figures to calculate the age of your chosen trees. Divide the circumference by the growth rate for your tree. A calculator may help!
For example, if your chosen tree is an oak tree that measures 110cm, you would need to do the following sum: 110 / 1.88 = 58.5 year (approximate!)
An oak tree would need a girth of about 900cm (9 metres) to have dated from the time of Henry VIII - (900 / 1.88 = 480 years: c1530).