A riding horse belonging to the Prior of Saint Botolph, which he loans to the wounded Ivanhoe so he can follow King Richard through the forest as quickly as possible. It's on this horse that Ivanhoe finds King Richard meeting with the outlaws in the wake of Waldemar Fitzurse's assassination attempt.
This is the guy who's apparently responsible for looking after Ivanhoe after his rescue from Torquilstone and locking up Athelstane in the basement of the Priory of Saint Botolph after Athelstane's apparent "death." Athelstane gets his revenge by locking up the Prior in his basement for three days and forcing him to live on bread and water so the Prior can see how it feels. For more on the events at the Priory of Saint Botolph, check out our "Character Analysis" of Athelstane.