File:18 Juin 1815 – Waterloo – Field of Waterloo. From the Picton Tree.jpg

English: Etching by William Miller (1796-1882), reproducing a (privately owned) 1817/1818 watercolour by J. M. William Turner (1775-1851), based on sketches he made during a one-day stay at Waterloo in 1817.

Quite surely wouldn't one expect J. M. W. Turner to record every minute details he had observed. Nevertheless, there is no mistaking in recognizing La Haye Sainte Farm seen from the North-East, precisely from the remnant of the Picton Tree.
As to the state of the tree, a ca. 1840 etching ►(File:18 June 1815 – Waterloo – L'Arbre Picton.jpg) is certainly closer to reality. Incidentally, the southwards (right to left) downhill slope of the road (future N.5) is exaggerated, and, beyond the farm, the road is level in real.

Far more importantly, J. M. W. Turner renders his perception of the battlefield, when still bare – the first monuments were to be built in 1817, 1818, and 1924-26 on and around the 18 June 1815 main Allied firing line – all three shown on the etching mentioned here-above.

In the valley, on this side of the road, about 4000 soldiers, all victims of that single 18 June 1815 combat for La Haye Sainte, rest in a common grave – but no stele, nothing recalls them.
Most information is confined to ancient documents : ►(File:Plate L from 'An Historical Account of the Campaign in the Netherlands' by William Mudford (1817).jpg).