康斯特布尔画他的风景画许多全面的初步草图，以测试组成提前完成的图片。这些大型草图，用自己的自由与活跃的笔法，是革命性的时候，他们继续兴趣的艺术家，学者和普通公众。该油草图中的一匹跃起的马和干草车，例如，传达出活力和表现力，从警员的科目相同的成品画失踪。可能比警员的工作的任何其他方面更多，油草图揭示他回想起来已经是一个前卫的画家，一个谁证明了山水画可以在一个完全新的方向服用。Constable draws many comprehensive preliminary sketches of his landscape paintings to test the composition of pre-completed pictures. These large sketches, with their own free and active brushwork, are revolutionary when they continue to be interested in artists, scholars and the general public. A jumping horse and hay cart in the oil sketch, for example, conveys vitality and expressiveness, and disappears from the finished painting of the same subject as the police officer. Perhaps more than any other aspect of the police officer's work, the oil sketch reveals that he recalls to be an avant-garde painter, who has proved that landscape painting can be used in a completely new direction.