Lydia Delaval - wife of Réginald Dunstanville de Dunstanville, 1st Earl of Cornwall?

Lydia would be a very unusual name for the time. It's one of those New Testament names that first becomes popular in the 17th century with the Protestants.

The publication date of this book is MDCCXC -- 1790.

I wonder if it's one of those cases where a document said 'descended from' or 'related to' in latin and was erroneously translated as 'daughter of.'

Ref. Mervyn Archdall: The Peerage of Ireland, Vol VII [1789] - a revised and enlarged version of John Lodges editon [1754] (https://play.google.com/store/books/details?id=eYsUAAAAYAAJ&rdi...):
"Sir Henrick Delaval, second son of Guido, was of the number of those Knights who carried the head banners, when his kinsman William, Duke of Normandy, conquered England. — He married Gunnirilla, daughter of Roger de Beamont or Bellamonte, ancestor to the Earls of Mellent ; by his said wife he had Henrick or Henry his heir ; and a daughter Lydia, who married Reginald, Earl of Cornwall, natural son of K. Henry I."

Some of the signs this is a probable fake are:

1. She has the name Lydia, which is not documented anywhere else in western Europe before the 16th century.This misunderstanding about when names began to be used is a common feature of forgeries in the 16th through 18th centuries.

2. The citations to her come from peerage books compiled before Oswald Barron (1868-1939) started demolishing the old myths in those books.

3. She is not included in modern references or peerage books, on Medlands, on Genealogics, in SGM, or anywhere else that I can find.

4. Her surname Delaval is always given in the English form instead of the French form (de Laval).

5. There is no contemporary evidence of her supposed father Sir Henrick Delaval, and no evidence that such a man took part in the Conquest, that such a man was a relative of William the Conqueror, or that Roger de Beaumont had a daughter Gunnirilla.

6. Her grandfather Guido (an Italian form for the French Gui) is supposed to have been lord of Seaton Delaval in Saxon England a generation before the Conquest, but is not named in any contemporary source and his presence would be highly unlikely.

7. This undocumented Delaval family is supposed to have been using a stable and hereditary surname at a time when surnames were just beginning to emerge among the highest nobility -- at least according to the dating on Geni, where Sir Henrick is born 125 years before his son-in-law.

Very odd. This is one connection I would want to see firmly documented in contemporary sources before accepting it.