The Marble Hill Black Walnut

In 1907 the standard survey of British trees ranked this walnut first of its kind in the country. Elwes and Henry, in The Trees of Great Britain and Ireland, recorded it in 1905 at 98 feet tall with a trunk 14 feet 3 inches round. Owen Johnson of the Tree Register measured it again in 2001: 27 metres tall and 184 centimetres across the trunk, which works out at roughly 5.8 metres round. A century had taken a few metres off the top and added well over a metre to the waist. The Tree Register's verdict, as quoted in John Grimshaw's garden diary, is that no other black walnut in England matches it for both height and girth with a full canopy. It was among the original 41 Great Trees of London. Its age rests on a story. Tradition, repeated by Grimshaw, says Henrietta Howard planted it in the 1720s, and a London parks survey thinks it probably belongs to the park's original landscaping. Neither is a planting record, so roughly 300 years, somewhere between 250 and 320, is as close as anyone can honestly put it. The pin comes from the Great Trees coordinate and is approximate. The park's own description puts the tree near the entrance from the Thames towpath, so start there. Marble Hill Park is free and open daily from dawn to dusk; the house is ticketed separately. St Margarets and Twickenham stations are each about 15 to 20 minutes on foot.