This oil on canvas study depicts Sir John Brydges, a historical figure who served as constable of the Tower of London during Lady Jane Grey's imprisonment. The painting functions as a preparatory work for a larger composition documenting the execution of the young queen in 1554, allowing the artist to develop the characterization and positioning of this key witness to the tragic event. The unlined canvas suggests the work's status as a sketch or study rather than a finished exhibition piece, preserving the immediacy of the artist's initial compositional thinking.