He wrote an account of this period which provides information about the theory and practice of military justice in the early 19th century.
[1][2] Larpent studied for some time under John Bayley the special pleader, was called to the bar, and went the western circuit, but did little business, but made some useful friendships.
A new code was in course of formation, and Larpent was employed for a month or two in arranging the court-martial on General Sir John Murray.
[1] In the spring of 1815 Larpent was invited by the Prince Regent to inquire into the improprieties which Princess Caroline was alleged to have committed abroad, but he insisted that his appointment should proceed from the government directly, and that he should not be employed to gather partisan evidence.
Although he nominally set out to take up his work at Gibraltar, he went to Vienna, where he was accredited to Count Münster, and began his investigations into the princess's conduct, with the result that he dissuaded the prince's advisers from bringing her to public trial.