I think that this photograph might relate to the funeral of 'Superintendent Townend'. A riderless horse or caparisoned horse (in reference to its ornamental coverings)is a single horse, without a rider, and with boots reversed in the stirrups. This often accompanies a funeral procession. It cannot be a reference to the police officer shown in the photo. His rank is that of a Constable (Second Class) and indicated by the single inverted chevron on his lower right sleeve.