Did Moriarty consult the Giffard pedigree in the 1566 Oxford Visitation?

While I don't currently have access to the NEHGS website (including
the back issues of _The Register_), I believe the following line of
descent taken from an old soc.gen.medieval posting agrees fairly well
with G.A. Moriarty's article(s) on the Giffard line behind William
Sargent:

1. LUCY DE MORTEYN, daughter of Sir John, married Sir John Giffard
(the name being later changed to Gifford). He was of Twyford, Co.
Bucks, born 1301, died 1368. He married 2d, after 8 March 1361,
Alice----. Reference: vols. 75 and 79, "The New England Register."

2. SIR THOMAS GIFFARD, Knight, born about 1345, died 1394; married
about 1361, Elizabeth de Missenden, who died 1367. He married 2d,
Margery----; 3d Sybil----.

3. ROGER GIFFARD, son of Sir Thomas, born about 1367, died 14th April
1409; married (1) Joan de Bereford, who died not later than 1399;
married (2) Elizabeth----; (3) Isabel Stratele.

4. THOMAS GIFFARD, born 1408, at Fri(n)gford, co. oxford, died 29 May
1469; married Eleanor Vaux, daighter of William Vaux, Esq.

5. JOHN GIFFORD, born about 1431, died before 23 September 1506;
married (1) Alice; married (2) Agnes Winslowe, daughter of Thomas
Winslowe, of Bigbee, co. Oxford.

The Oxford Visitation pedigree claims that the wife of Sir Thomas
Giffard (#2) above was "Sibilla dna. de Newton Juell in Com. Oxford,"
and that Sibilla was the only wife as well as mother of the heir,
Roger. The account given just above gives Sir Thomas three wives:
"married [1st] about 1361, Elizabeth de Missenden, who died 1367. He
married 2d, Margery----; 3d Sybil----."

See
http://books.google.com/books?vid=OCLC03975611&id=ifhx0ZD7yVsC&pg=RA8-PA362&lpg=RA8-PA362&dq=%22margaret+gifford#PRA6-PA177,M1

Did Moriarty in his article(s) specifically refute the idea that
Sybil, lady of Newton Juell, was the ancestress of the later
Giffards? What family would Sybil have belonged to?

There are a few other differences between the two pedigrees. As these
Giffards were mainly in Bucks. and Northamptonshire, Moriarty may not
have thought of looking at the Oxfordshire Visitation.

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