Career
Pennefather was commissioned as an acting lieutenant in the Royal Marines in 1965. He was appointed Commanding Officer of 42 Commando in 1988, Commander of 3 Commando Brigade in 1992 and Commander of the United Nations Rapid Reaction Force during the Bosnian War for which he was appointed a Companion of the Order of the Bath. He went on to be Commandant General Royal Marines in 1996 before retiring in 1998.
In retirement he became Secretary of the Royal Humane Society and a director of the Royal Naval Museum in Portsmouth.