Deep within Sherwood Forest in Nottinghamshire, a huge, gnarled tree spreads its crooked limbs out over a small clearing. This is the Major Oak, the most visited tree in Britain – and probably the most famous. Weighing around 23 tons, with a trunk girth of 10 metres, and a canopy of 28 metres, it’s the largest oak tree in the country. And, at between 800 and 1,000 years old, it’s also one of our oldest. But these are not the primary reasons for the Major Oak’s popularity.