That was a jockey.

Karl Pilkington’s Monkey Who Rode a Horse 

During Karl Pilkington’s “Monkey News” segment on XFM’s “The Ricky Gervais Show,” the bald, orange-headed Manc informs his listeners about “what’s been going on” in the simian world.
During the 10th episode of the first season, Karl told the story of a monkey that rode a horse and subsequently won a horse race for a local gangster. Somehow, no one ever noticed that the jockey was a monkey – until it tried to eat a fake banana from a woman’s hat in the winner’s circle.

What this Monkey News teaches us:
The origin of the phrase “Put a monkey on it.”

Monkey Jockey 
This is proof: If a monkey can ride a dog then it can definitely ride a horse.