Thanks for the corrections and additional information.
The records of Christ Church in Middlesex County, Va show Mary Goodloe married 21 July 1720 to William Johnson. The Goodloe Family Bible says Mary Goodloe married 21 July 1720 in Middlesex Co. to Buford Johnston. From this we have assumed (with some reasonable thinking) that he was William Buford Johnston. The "t" gets omitted in most records (a problem even in modern times for me and others).
There was another William Johns(t)on in the same area at the same time that married Ann (Nan) Chew and for many years we had a difficult time sorting those two out and often their children got mixed in various records.

It was with the discovery that the Goodloe Family Bible was passed down one of our Johnston lines that we were able to say with some certainty that our line was from William that married Mary Goodloe. I regret I have never seen this Bible and only have some notes taken from in the 1940's by a cousin who was doing reserach at that time. It has since "disappeared" and is in the hands of a branch of the family that is unfortunately not very cooperative. It is somewhere in Mississippi and I have hit a dead end in trying to get anyone to admit to having it. If I ever win the lottery I will offer a large reward for seeing it and perhaps that might make it emerge once again. By the way, this is the family of current MS Gov. Haley Barbour who is my 5th cousin. I have spoken with his brother and another cousin in that line, but no one seems very interested in helping locate the Goodlow Bible or Wakker Prayer Book, although they agree it must be somewhere in their branch of the family.

As it is, We know my ancestor Henry Johnston (probably named for his maternal grand father Henry Goodloe) married Agnes Carr Waller. They named their youngest son, Henry Goodloe Johnston (b. 30 Aug. 1782) and he was given care of both the Goodloe Bible and the Waller Family Prayer Book, which he took to Mississippi with him after the death of his mother in 1832 in Spotsylvania Co., VA. He had moved to MS in 1810, having married the dau. of the territorial govenor, but he returned to VA for the settlement of his mother's estate. His brother older brother, Thomas Buford Johnston (my line) had moved to Kentucky but did not return to VA but allowed Henry Goodloe Johnston to act as his representative.

Henry Johnston (b. 1727) had an older brother named Stephen (b. 1721) We can connect these two only because of an entry in the records of a Captain Edward Dixon, merchant of Port Royal, Caroline Co., VA. In his ledger 1743-1746, p. 210 is the account of Henry Johnson, 1746 "brother of Stephen Johnson".

Stephen was born 1721 and Henry in 1727, so there may be other siblings between them that we do not know about. William Buford Johnston apparently died intestate 4 June 1728 in Spotsylvania Co. It is from the notes taken in the 1940's from the Goodloe Bible that we find that his widow Mary then married Henry Daniel.

William Buford Johnston may also have been previously married to a Mary Huddleston, although I can not find proof he is the same as that William Johnson. But, later our Henry Johnston (b. 1727 and m. to Agnes Carr Waller) is made guardian to the minor children of Jeremiah Stevens (Stephens) and there is speculation that Jeremiah's wife may have been an older half sister to Henry.

At this time, William Buford Johnston is our "brickwall" and although I speculate he was born in Virginia, I can not say that with certainty.