It was part of the annual sitting of the Court of Chief Pleas, which marks the start of the legal year.
Megan Pullum QC took the oaths as HM Procureur and HM Receiver General while Robert Titterington did likewise as the new HM Comptroller.
Bailiff Sir Richard Collas said everybody was witnessing a moment of history with the installation of the first female HM Procureur.
During her previous four-and-a-half-years as HM Comptroller, Ms Pullum had earned universal acclaim for the solid and pragmatic advice she had given and for the way she had discharged her duties in such an exemplary manner.
He said the task of leading the team at St James Chambers had grown in content and complexity.