He had sinned much, had been forgiven much, and so he loved much. In Satans service he had often exposed himself to disgrace, danger, and death itself. But of his life after his conversion, the editor of his autobiography says " If there had been need for it, I believe there was no man in Edinburgh who would have gone to the stake or scaffold for Jesus Christ with a firmer step or nobler bearing than this brave old soldier of the cross."
Converted in India, while a soldier, Flockhart was fearless as a street preacher often in the face of unruly crowds. He was uniquely gifted as a natural orator with a true genius for picturesque language.
From his autobiography:
Compassion to the souls of men drove me to the streets and lanes of my native city, to plead with sinners, and persuade them to come to Jesus. In my preaching I dwelt upon death and its consequences, the everlasting punishment that awaited ungodly and impenitent sinners, and the everlasting weight of glory that was laid up for the righteous.
He was found every week-day evening at his post at the west-end of St. Giles cathedral, and on the Sabbath evenings in front of the Theatre. The weather was all one to him in frost, in snow, in rain, as well as in sweet summer eve, he might be seen about nine oclock slowly wending his way to his post. He began by singing a few verses of a psalm; this had the effect of arresting attention, and at length of gathering an audience. With the crowd around him, composed chiefly of outcasts, he would break the bread of life .