In 1765, Gandon left William Chambers to begin practice on his own. His first commission was on Sir Samuel Hellier's estate at the Wodehouse, near Wombourne. Gandon's new practice, whilst successful, always remained small. In about 1769 he entered an architectural competition to design the new Royal Exchange in Dublin. The plan eventually chosen was by Thomas Cooley. However, Gandon's design came second and brought him to the attention of the politicians who were overseeing the large-scale redevelopment of Dublin, one of the largest cities in Europe at the time.