Matilda, countess of Chester (d. 1189)

The current online version of the ONDN biography of Matilda (1), wife of
Ranulf (II) earl of Chester notes that she "was the granddaughter of
Henry I by his illegitimate son Robert, earl of Gloucester (d. 1147),
and Sibyl, the daughter of Roger de Montgomery, earl of Shrewsbury (d.
1157)".

This looks fine to me until we get to Sibyl. I understand (2) that
'Mabel of Gloucester' was called 'Matilda' by Oderic Vitalis and 'Sibyl'
by Robert de Torigni, so we can allow that that Robert's wife might have
been a Sibyl in some sources, but I have her as not daughter but
grandaughter of Roger de Montgomery. I have Mabel/Sybil's parents as
Robert fitz Haimon and another Sibyl who was the daughter of Roger de
Montgomery and Mabel de Bellême.

Who's wrong?

mjcar...

Actually, doesn't it depend on how you read the statement in ODNB? You
are asserting [correctly] that Matilda, Countess of Chester's mother
(the wife of Robert, Earl of Gloucester) was the granddaughter of
Roger, Earl of Shrewsbury, i.e. that Matilda was Roger's great
granddaughter.

ODNB says that Matilda was "the granddaughter of Henry I... and (of)
Sibyl, the daughter of Roger..., Earl of Salisbury.", ie that Matilda
was Roger's great grandddaughter.

You are both correct.

(1) Susan M. Johns, ?Matilda, countess of Chester (d. 1189)?, Oxford
Dictionary of National Biography, Oxford University Press, 2004

(2) Judith A. Green, ‘Robert fitz Haimon (/d./ 1107)’, /Oxford
Dictionary of National Biography/ , Oxford University Press, 2004