Dicky Diaper forming a right angle [graphic]

A rider sits stiffly on a misshapen horse that wears blinkers. The rider's stirrups almost touch the ground, and his body and legs form a quasi-vertical line from head to heels. Above his hat is a dotted half circle labeled '90 degrees'. On the right in the middle distance another horse gallops out of control of its rider while further on top a hill in the distance is St. Paul's Cathedral and surrounding buildings