Duncan eventually made his way to Glasgow. Robert Cleland, writing in 1816, asserts that Duncan founded the Episcopalian congregation in the city in 1715 (the congregation now at St Mary's Cathedral), but there are several references to Duncan earlier than that. Documentary evidence is fragmentary, but it is likely that the Episcopalians of Glasgow had formed a discrete congregation from the time of the Revolution, and over the following years several clergy were attached to it. Duncan attended the deathbed of the young Lady Dundonald in nearby Paisley in 1710, and his name is included in a list of Glasgow’s Episcopalians dating from 1713, a list which also includes John Walkinshaw of Barrowfield (father of Clementina Walkinshaw, Sir John Bell and John Barns, former Provosts of Glasgow, and Sir Donald MacDonald of Sleat. During this period it seems that the congregation met mainly in private houses, including Sir John’s lodging in Saltmarket and probably in Barrowfield. A meetinghouse-chapel opened in 1712 was destroyed by a mob a few days after the death of Queen Anne in 1714. In 1715 several members of the congregation fought under James Edward Stuart at Sheriffmuir.