Windmill drawing found on wall of Isaac Newton childhood home

Scratched image discovered at Woolsthorpe Manor using method that reveals detail invisible to the naked eye

A friend of Isaac Newton once described him as a compulsive scribbler on walls. Almost 300 years after the scientist's death, a wobbly drawing of a windmill has turned up, scratched into a wall at his childhood home.

The image was found during a conservation study at Woolsthorpe Manor in Lincolnshire, now owned by the National Trust, where there is also an apple tree said to be the one that inspired Newton's theory of gravity.