The bronze monkey was a statuette modelled by Marc-Antoine Duparc and cast by Barbedienne.
Falcondale told Horley a number of stories regarding the statuette, though Grinstead states many of the stories are merely conjecture. According to Falcondale, after its initial design and casting by Duparc and Barbedienne, the monkey was bought by the Duc de Sèvres and was bought and re-sold a number of times, at one point being exhibited as part of a show of Parisian bronzes in London acquired by the Maeterlinck Gallery. According to a letter Horley cites, it was also involved in a Russian scandal in which it was used as a murder weapon. It was then displayed in a Moscow art gallery alongside the painting of Marisa Van Zee. Eventually, it was owned by Rainsford and given to the art collector Horley as repayment for a debt owed for a Charpentier mezzotint.
On the night fellow art collector Grinstead visits Horley at his Oxford College, Grinstead steals the painting but leaves the monkey, reflecting that it will follow in its own time, before being hit by a taxi on the Oxford High Street. At the finding of his body, the portrait is returned to the College beside the statuette in the possessions of Horley, who died the same night.
The statuette was about a foot high and depicted a monkey with its arms outstretched as if reaching for something. It was very detailed, down to the fingernails and hairs. The body seemed to show tension, as if it were about to spring, and its face bore a savage expression that repulsed many who saw it.