James Ley, 3rd Earl of Marlborough
James Ley, 3rd Earl of Marlborough is buried in the north ambulatory of Westminster Abbey but he has no monument or marker. His grave is near that of Dr Duppa. The Abbey Precentor's book states that the fees for his funeral were waived "as he died poor and his friends [were] not able or not willing to pay the money, they gaining nothing by his death". So there was obviously no money for a gravestone.
He was a naval officer, son of Henry, 2nd Earl of Marlborough and his wife Mary (Capel). As a young man he travelled to America and was later admiral of a Royalist squadron. He became commissioner of trade for the colonies and commanded an expedition to Bombay in 1662. He was killed fighting the Dutch at the battle of Lowestoft in the ship Old James and was buried on 14th June 1665. He died unmarried and his uncle William succeeded to the title.
Oxford Dictionary of National Biography 2004