General Notes

Sir Ralph Brereton of Brereton, Knight, said in some pedigrees to
  marry Ada, daughter of David, Earl of Huntingdon, and his wife Maud or
  Matilda, daughter of Hugh de Keveliock, Earl of Chester. This gives the
  Breretons Royal Descent because she was great-granddaughter of David,
  King of Scotland, and maternally the Earls of Chester were Royal Earls,
  who possessed jura regalis in the Palatinate of Chester. They also laid
  claim to royal descent from the Venables, who was a relation of Stephen
  of Blois and William, the Conqueror. At first the descent of the Breretons
  from the royal blood of Scotland was mentioned as a mere claim,
  which was found in Collins' Peerage and in Dugdale's British Peers, but
  a copy of the patent or grant of creation to Sir William Brereton, of the
  Barony of Brereton, has since been procured and in that instrument such
  royal descent in Scotland is expressly recited and recognized in the following
  terms: "We, considering with mature deliberation the free and
  true services of Sir William Brereton, and that he is sprung from an
  ancient, noble and most renowned family, inasmuch as he is descended,
  through many illustrious ancestors, from Ada, sister of John, surnamed
  le Scot, 7th Earl of Chester, and daughter of David, Earl of Huntingdon,
  Lord of Galloway, within our kingdom of Scotland." (This quotation is
  found in Archaeologia, or Miscellaneous Tracts Relating to Antiquity,
  Vol. 33, p. 59.)