Sir William Cuninghame, 1st and Last Earl of Carrick, so created c1362, but seemingly resigned the title to the Crown by 1369; married Margaret and died after Dec 1396 but before July 1399. [Burke's Peerage]
---------------Dorothy Cuninghame Ancestry by Suzanne Doig, www.geocities.com-----------------
2. Sir William de Cunynghame of Kilmaurs, Earl of Carrick; married (1) Lady Eleanor Bruce (died 22 June 1368), daughter of Alexander, Earl of Carrick and Margaret Douglas; married (2) before 18 Apr 1369, Margaret. William died between Dec 1396 and Jul 1399.
William was Hugh's successor and was probably his son. He was created Earl of Carrick in 1361 by King David II Bruce, probably by virtue of marrying Lady Eleanor Bruce, cousin to the King. She ought not to have received the title as it was restricted to the male-line heirs of Edward Bruce, but exception was made for her. This title reverted to the Crown on the death of Lady Eleanor, in William's own lifetime. Some sources doubt the existence of Eleanor but do not explain how William could otherwise become earl.
Burke notes: "The charter in his favour is on record, and singularly incomplete, as if there had been a doubt as to the propriety of the grant:- 'David, D.G. Rex Scottorum, sciatus nos dedisse concessisse et hac presenti-carta confirmasse dilicto consanguineo nostro Willielmo de Cuninghame militi totum comitatum de Carryk.' ". The charter is not dated but was probably written at Aberdeen on 12 September 1361.
Children (probably by Eleanor):
Robert de Cunynghame, died young
Sir William de Cunynghame of Kilmaurs (#3)
Thomas de Cunynghame => the Cuninghame family of Caprington
Alexander de Cunynghame
John de Cunynghame