He was at first the Grand Secretary, and afterward the Deputy Grand Master, of that body of Freemasons who in 1751 formed the Grand Lodge of the Ancient, which see, stigmatizing the regular Freemasons as Moderns. In 1756, Dermott published the Book of Constitutions of his Grand Lodge, under the title of Ahiman Rezon; or a help to ad that are or would be Free and Accepted Masons, containing the quintessence of ad that has been published on the subject of Freemasonry. This work passed through several editions, the last of which was edited, in 1813, by Thomas Harper, the Deputy Grand Master of the Ancient Masons, under the title of The Constitutions of Freemasonry or Ahiman Rezon.
Dermott was undoubtedly the moving and sustaining spirit of the great conflict which, from the middle of the eighteenth to the beginning of the nineteenth century, divided the Freemasons of England; and his reputation has not been spared by the adherents of the constitutional Grand Lodge. Lawrie (History of Freemasonry, page 117) says of him: "The unfairness with which he has stated the proceedings of the moderns, the bitterness with which he treats them, and the quackery and vainglory with which he displays his own pretensions to superior knowledge, deserve to be reprobated by every class of Masons who are anxious for the purity of their Order and the preservation of that charity and mildness which ought to characterize all their proceedings."
There is perhaps much truth in this estimate of Dermott's character. As a polemic, he was sarcastic, bitter, uncompromising, and not altogether sincere or veracious. But in intellectual attainments he was inferior to none of his adversaries, and in a philosophical appreciation of the character of the Masonic Institution he was in advance of the spirit of his age. It has often been asserted that he invented the Royal Arch Degree by dismembering the Third Degree, but that this is entirely unfounded is proved by the fact that he was Exalted to the Royal Arch Degree in 1746, while the Degree was being conferred in London before 1744 (see Royal Arch Degree). Dermott was born in Ireland in 1720, initiated in 1740, installed Worshipful Master of Lodge No. 26 at Dublin in 1746, was Grand Secretary of the Ancient from 1752 to 1771 at London, the Deputy Grand Master from that year until 1771, then once more Deputy from 1782 to 1787, dying in 1791 An excellent, if brief, biography of his Masonic career has been written by Brother W. M. Bywater and was privately printed in 1884 at London under the title of Notes on Law: Dermott G. S. and His Work. Another essay, equally delightful, on Laurence Dermott, is by Brother Richard J. Reece, Secretary of the Grand Masters Lodge, No. 1, of England.
Brother Arthur Heiron's pamphlet, the Craft in the Eighteenth Century, says that "Dermott was musically inclined, and very fond of singing at the meetings of his Grand Lodge but that he was not always popular amongst the Ancient is proved by the fact that in 1752 four of their members accused him of having 'actually sung and lectured the Brethren out of their senses,' but in 1753 the W. M. in the chair at an Emergency held at the King and Queen, Cable Street, Rosemary Lane, thanked him for his last new song and 'hoped that the applause of his Brethren would induce Brother Dermott, G. S., to compose another against the next St. John's Day."'
- Source: Mackey's Encyclopedia of Freemasonry