Laurence Dermott was born in Ireland and became a Freemason in 1741. He held various offices before being installed as Worshipful Master of Lodge No. 26 in Dublin on 24 June 1746. He moved to London in 1748, possibly working as a journeyman painter, and possibly with a view to expanding his father's business. He would later work as a wine merchant, like his father.

The Ancient Grand Lodge of England, as it is known today, or The Grand Lodge of the Most Ancient and Honourable Fraternity of Free and Accepted Masons as they described themselves on their warrants, was a rival Grand Lodge to the Premier Grand Lodge of England. It existed from 1751 until 1813 when the United Grand Lodge of England was created from the two Grand Lodges. They are now called the Antients, in contrast to the Moderns, the original Grand Lodge which its critics, notably Laurence Dermott, said had moved away from the ritual of Scotland, Ireland, and now the Antient Grand Lodge. This Grand Lodge was also informally called the Atholl Grand Lodge because the Third and Fourth Dukes of Atholl presided over it as Grand Masters for half of its 62-year existence.