Many trees on West Ardnamurchan, especially those that stand alone in exposed places, are lopsided, like this silver birch near Achosnich. It's a consequence of living with the gales that burn their up-wind side, either by wind-chill or by depositing salt on their summer leaves.
The position this oak has adopted needs a different explanation. It is to be found in a narrow, sheltered glen cut by the Allt Nead an Fhir-eoin to the southeast of Glendrian, and looks as if it grew vertically but later flopped over. Perhaps it's a victim of a process called soil creep but, since this is usually very slow acting, while the lower trunk may be at an angle, the upper part of the tree remains fairly upright.
On the other hand, maybe this tree just wanted to be different, so it became the world's only horizontal tree.