Reverend Nathaniel Irwin succeeded the prior pastor in 1774, and remained until his death in 1812. He was a man of varied and extensive information, possessed great scientific knowledge, and was passionately fond of music. He exercised a wide influence in church and state, and for several years he controlled the politics of the county.

He was instrumental in having the county seat removed to Doylestown. As a slur upon the clergy and church for interfering, some one made a charcoal sketch on the walls of the old court-house at Newtown, which represented Mr. Irwin in his shirt sleeves with a rope around the building and his body, and he pulling in the direction of Doylestown with all his might.

During his pastorate, in 1775, the church was enlarged. In his will he left $1,000 to the Presbyterian theological seminary, on condition that it be located on the site of the Log college, and $500 to the American Whig society of Princeton college, of which he was one of the founders in 1769.

He rode to church on an old mare called Dobbin, and composed his sermons as he jogged along the road and across the fields.