Who is Perce Blackboro, stowaway (later steward) from Endurance: Shackleton's Incredible Voyage and what is their importance?

Blackboro, a friend of expedition-member William Bakewell, joins Endurance in Buenos Aires as a temporary-duty hand. Desiring to accompany the expedition but refused permanent employment, he contrives to stowaway with Bakewell's help—he is nineteen years old at the time. When Blackboro is discovered, Shackleton, only half-jokingly, promises that Blackboro is to be the first man eaten should the expedition have to resort to the necessity of cannibalism to survive. Subsequent to this inauspicious start, however, Blackboro becomes a valuable crewmember and serves well on the expedition.