Hi! The Magna Carta project focuses on the works of Douglas Richardson - specifically, the 240 Gateway Ancestors listed by Richardson in his Magna Carta Anctestry. George Barnes is not one of those listed. Therefore, he's not within the scope of the main project & not listed at Base Camp. If you believe he has a provable lineage to Magna Carta Surety Barons, check out the Questionable Gateway Ancestors.
Doing a cursory search of Douglas Richardson's Plantagenet Ancestry: A Study In Colonial And Medieval Families, 2nd Edition, 2011, I found on page 55, note 38, that Charles Barnes of East Hampton, Long Island, is the descendant of Gilbert De Clare and Joan of Acre.