William Tucker came to prominence in the 1960s after training under Anthony Caro at St. Martin's School of Art in England. He was associated with the New Generation Sculptors and is considered a seminal figure in contemporary British sculpture. Tucker's early works are made from steel and recycled wood and were based on abstract, geometric shapes that incorporate large areas of negative space. His skeletal, geometric frames gave way to solid compositions cast from plaster and concrete. His increasing concern with nature and the human form led him to use more malleable materials and organic compositions. Tucker describes his later works as having "a more human presence, while not being figurative in a familiar sense."
Horse X belongs to his sculptural series of horse heads produced since the 1980s. Tucker credits the ancient Chinese equestrian horse sculptures at Boston's Museum of Fine Arts as his inspiration, and mimics the green patina of the ancient small bronze sculptures in his own monumental works. The organic quality of the sculpture resembles natural rock formations, and contrasts with the hard edges of his earlier geometric works. The horse's head is abstracted but the title of the work helps to reveal the sculpture's figural qualities.