John Macmillan was the first Covenanter minister following the Glorious Revolution. He was born in 1669, and while a student in Edinburgh he had been connected with the United Societies . Nevertheless, after finishing his studies he became a minister in the Church of Scotland. However, he soon got in trouble for speaking in favour of the covenants and he was removed from being a minister in 1703. Three years later, he accepted a call to become the first minister to the United Societies since James Renwick and Alexander Shields, sixteen years earlier. From then on, McMillan travelled about the country, preaching to the 10,000 scattered members of the societies, conducting weddings and baptising. In 1712, the societies renewed the covenants (National and Solemn League) at Auchinsauch.

In 1743, Rev. Thomas Nairn joined the societies. Now they had two ministers, the United Societies could finally form a Presbytery. The United Societies then became known as the Reformed Presbyterian Church. A Synod was formed in 1811.

Read more:
Matthew Hutchison, The Reformed Presbyterian Church in Scotland: its origin and history, 1680-1876 (Paisley, 1893) pp 140-193
Testimony of the Reformed Presbyterian Church of Scotland: Historical and Doctrinal (Glasgow, 1866 [1837, 1839]), pp 115-6, 124-29
DSCHT: Macmillan, John; Nairn, Thomas; Reformed Presbyterian Church