On Sunday, 14 September 1721, the Reverend William Robertson, minister of Borthwick, administered the sacrament of baptism, as he had done many Sundays before. The small parish church, an old “popish building in the form of a cross” built in a plain Norman style dating to the middle of the twelfth century, was dilapidated, as were many of the churches of early eighteenth-century Scotland. Yet despite the modest setting, this was an important occasion for the minister, for the child to be baptized was his first child, a son born six days earlier. He was also to be named William, and he would become one of the best known figures in eighteenth- century Scotland. With the minister as witnesses of the baptism were four of the most prominent heritors of the church from around the parish of Borthwick: from the south John Mitchelson of Middleton; the west James Dalrymple of Harviston; the north Walter Welsh; and, most prominent of all, Robert Dundas, Lord Arniston, the parish patron whose estate lay in the far western corner of the parish. Lord Arniston's attendance was a particular honor because at this time his health was failing, and he was suffering severely from gout.

The minister was not new to the Borthwick community, having been ordained to the parish in 1714. Born in 1686 in Fife, where his father, William Robertson of Gladney, was a factor on the Wemyss estate, he had been granted a license to preach by the presbytery of Kirkcaldy in 1711. First ordained to Founder's Hall in London (later to be called the Scots Church at London Wall), he served as an assistant to the prominent minister Robert Fleming. A close ally of William Carstares, Fleming was learned, tolerant, and versed in anti-Calvinist Arminian thinking. He was also coping with depression during 1712–14, requiring him to make a trip to the Netherlands to aid his recovery. Thus, although it is uncertain just how much contact Robertson actually had with him, the experience seemed to have left a mark on his thinking, giving a tolerant cast to his ministerial teachings.