This is a plaster cast of the original bronze head of Bartolomeo Colleoni (died 1475), from the equestrian monument in Campo SS. Giovanni e Paolo in Venice. Bartolommeo Colleoni (d. 1475) was a condottiere or mercenary leader, who had commanded the Venetian troops. In his will, he bequeathed a sum of money for this monument. The commission was awarded to Verrocchio in April 1480, but he left the statue unfinished at his death in 1488. It was cast by Alessandro Leopardi of Ferrara (1480- 96), whose signature appears on the girth of the horse. The plaster was cast by Elkington & Co. in Birmingham or London in about 1885.

Plaster casts were especially sought after during the 19th century, when reproductions of great works of sculpture and architecture were thought crucial for the training of artists. A separating substance was applied to the surface of the work to be reproduced, and a plaster mould made from that. The mould would then be used to make any number of additional plaster copies. These were often sold to artists, and later in the century to art colleges for study purposes.