Individual Details

John married Frances Lightfoot, an Indian. [I doubt this statement. A John Lighfoot, Esqr. was the Escheater for the Virginia Land Patent office in 1701-1705. So this surname does occur among the Englishmen living in Virginia at this time. The Escheator examined titles to the grants in the case of the death of the grantee.]

VIRGINIA COLONIAL RECORDS, 1600s-1700s, Genealogy.com online subscription.
Militia Lists, Public Record Office, London.
King & Queen Co ca 1701/02 William Leigh, Col. Henry Fox, Maj. John Fox, Lt.
King William Co, 20 Apr 1702. John West, Col. & Commander in Chief; Wm Claiborne, Lt, Maj. Thomas West, Capt of Horse, Thomas Claiborne, Capt of Dragoons, John Fox, Capt. of Foot.

Virginia Quit Rents, 1704. Henry Fox. 2000 acres, King William Co.
Capt John Fox, 600 acres, King William Co.
Margaret Fox, King & Queen Co, tax due, 100 acres.

I believe the following refer to this John Fox as his grandfather would have been deceased for some years. His brother Thomas had land adjoining that of Capt Nathaniel West:
CAVALIERS, Vol 3, p.168 23 Dec 1714 Thomas West, granted 1615 acres in King William Co, St. John's Parish. Begin at Capt Nathl West in Bull Swamp to Capt Jno. FOX., N side of Bridge, E side of Ferry Road, to Capt Martin Palmer, Col. Wm Claiborn's line, near Capt Thos Claiborn [John's sister Anne was the wife of Thomas Claiborne], Wm Burrous' land in Hollings line. Crossing the Long Br to Jno Higgason's line. . Import of 4 persons. PB 10, p.226

John Fox may have gone to Spotsylvania Co and died there in 1750 The following records likely refer to an entirely different John Fox since his wife was Mary and his kinsman was a James Fox.
CAVALIERS, Vol. 3
p.399. 26 Jun 1731 Martha Fry, grant for 1000 acres, lapsed land, in Spotsylvania Co, St. George's Parish. Both sides Robinson Riv. Granted to Joshua Fry, Gent. of Wm & Mary College on 11 Jun 1726, not seated and granted to John Fox who made over to said Martha. PB 14, p.203 [the earlier grant to Joshua Fry is on p.301; PB 12, p.402]

SPOTSYLVANIA COUNTY RECORDS 1721-1800, William Armstrong Crozier
Deed Book B 1729-1734
14 Jul 1730 Andrew Harrison to William Johnson. Harrison stands indebted to Johnson by cause of a judgment obtained by Jno. Fox and placed in the hands of sd Johnson as Sheriff. Harrison makes deed [mortgage] to Johnson for Negro boy, furniture, cattle, etc. Wit: Antho. Foster. Rec. 4 Mar 1734/5
Deed Book D 1742-1751
Deed not dated. Henry Goodloe, Gent, conveyed to George Goodloe of Caroline Co by deed 13 May 1735, 800 acres in Caroline & Spotsylvania, which was then devised by LW&T of George Goodloe, dec'd, dated 4 Oct 1741 to his three sons, Henry, George & Robert. Wit: Edmund Waller, John Fox, Nichl Hawkins. Robt Jackson, Thos Turner Junr, Benjamin Woodward. Rec. Aug 1748.
Deed Book D 1742-1751
16 Jun 1749 Thomas Howell of Fredericksburg, Blacksmith, to John Fox of Fredericksburg. Goods and chattels for 9#'s. [mortgage?] Wit: David Mitchell, John Lewis, John Simpson, Wm Hughes. Rec. 1 Aug 1749
Will Book B 1749-1759
JOHN FOX of Fredericksburg Will dated 10 Jan 1749/50; probate 6 Mar 1749/50. Wife, Mary to have my plantation in Prince William Co whereon Winshott lives. My kinsman, James Fox to convey to John Triplett the land in King George Co. Executors: wife Mary and kinsman James Fox.
Wit: M. Battalay, John Sutherland, Richard Tutt, James Sparks
[Note: there was a Fredericksburg in Spotsylvania Co as well as Augusta Co. The dating from Old Style to New Style had not yet changed and the dates of the Will as 1749/50 were actually late in the year of 1749, after the mortgage deed from Howell dated in Jun of 1749]

The kinsman, James Fox, is unknown. He did create some records in Spotsylvania Co.
Spotsylvania DB E 1751-1761
4 Dec 1750 George Woodruff, Planter, and Jane his wife to Rice Graves, planter. 10#'s. 100 acres in Spotsylvania Co. Wit: Robert Huddleston, John Smith, James Fox. Rec. 4 Dec 1751.
16 Jan 1752 William Williams of Culpeper Co and Lucy his wife to Roger Dixon. 330 acres descended to William by the LW&T of his father James Williams dated 30 May 1735. Wit: Pat. Connelly, Robert Halkeston, James Fox, Gabriel Throckmorton. Rec. 2 Jun 1752
Then by 1754, James Fox himself was deceased.
3 Sep 1754 Richard Peacock of Town of Fredericksburg, blacksmith, to Lewis Webb, Gent. & Administrator of James Fox, 16# owing to him for the shop and house where I dwell, blacksmith's tools, etc. No Wit. Rec. 3 Sep 1754.

Birth	Abt 1682
Death	1767

Father	Henry Fox I (1650 - 1714)
Mother	Ann West ( - )
Sibling	Henry FOX II (1674 - )
Sibling	Anne FOX (1684 - 1735)
Sibling	Thomas Fox (1686 - 1749)