|The vineyards of Cognac|
He was named Philip, probably after Richard's friend (and sometime adversary) Philip II of France. We don't know his birth date, but he was old enough in the 1190s to be married to Amelia of Cognac, heiress to Itier V, the Seigneur of Cognac* in Charente, in west-central France. When Amelia died, Philip inherited the castle, which later passes into the hands of his seneschal, Robert of Thornham, who had distinguished himself during the Crusades.
One wonders if Philip cared for his noble birth, or simply yearned for a quiet life. He does not keep the estate in Cognac, and we only see his name later in the Pipe Rolls (the financial records of the kings of England). In 1201, during the reign of King John, we find the entry: "And to Philip, son of King Richard, one mark as a gift." A report that there is a record of him "selling his lordship" to King John is just a rumor.
Roger of Hoveden claims in his Chronica that Philip avenged his father's death by killing the Viscount of Limoges, because the crossbow that led to Richard's death was fired while Richard was suppressing a revolt by Limoges. Hoveden's is the only reference to this event, however, and it seems unlikely, especially for a figure who seems so undistinguished and anonymous in all other ways. Except for life as a character in Shakespeare's King John, and as the potential successor to King John in the TV movie Princess of Thieves, Philip of Cognac has passed out of human memory...or interest.
*As you may guess, cognac brandy comes from this region.