↑This particular John Washington is often called "the immigrant John Washington" by various historians and authors, see Glenn Introduction for an example - "This is the vast family originated by the immigrant John Washington".
↑Glenn, Justin (2014). The Washingtons. Volume 1: Seven Generations of the Presidential Branch. Savas Publishing. p. 34. ISBN9781940669267. Although estimates of his birth date by modern researchers range from 1631 to 1634, Peter Walne has convincingly argued that John's parents were not married until November 30, 1633 or very soon thereafter. As Walne points out this was the date John's father Lawrence formally resigned his fellowship at Oxford and he had formerly taken an oath to remain unmarried as long as he held the fellowship.
↑Justin Glenn, The Washingtons: a family history (El Dorado Hills, California: Savas Beatie LLC 2014) vol. 1, pp.1-3