Then a village, approximately six miles west of the centre of London. From Wikipedia’s page:

Turnham Green was originally a village on the main road between London and the west. It was recorded as ‘Turneham’ in 1235 and ‘Turnhamgrene’ in 1369. On 13 November 1642, the Battle of Turnham Green was fought near here during the First English Civil War resulting in the Parliamentarians blocking the King’s advance on London. The artist William Hogarth had a ‘Country cottage’ nearby on what is now known as Hogarth Roundabout.