"in the robes of a Knight of Malta"

The Knights of Malta are a Catholic order. It has a range of different names including the Order of St. John, Knights Hospitaller and the Sovereign Military Hopitaller Order of Saint John of Jerusalem of Rhodes and of Malta. 

The order, founded in the 11th Century, was originally a community of monks who cared for the sick at the Hospital of St John in Jerusalem, although it later became a military order of knights.

Having evolved over many centuries, the order is still in existence today.