There is no evidence that I can find as to why this short tunnel exists hidden in the middle of Sherwood Forest but having carried out a little research Williams Siemens, who co-founded the Siemens electrical engineering company with his brother Werner in 1858, lived at Sherwood Park from 1874 until he died in 1883. He was a pioneer and inventor similar to David Salomons and in his short 9 year period there, made many changes to the grounds of the house which could possibly explain why this tunnel exists. It is nearly inaccessible due to tree roots and leaves blocking the entrance but having squeezed myself inside there would be room to stand if it wasn't half full of soil. It doesn't go back too far as unfortunately the tunnel has caved in around 3 metres or so from the entrance.