Mackcoull now considered himself beyond all danger, and in company with one Harrison, made several trips to Scotland, and purchased commercial bills in the name of James Martin, a merchant, and everywhere introduced his friend Harrison as a most respectable person. In 1812 he opened a deposit account with Messrs. Marsh and Co. bankers, in the name of James Ibel, and had in their hands at one period above 2000_l._
In March 1813, he again visited Scotland to vend more of the stolen notes, but was taken into custody, and bills and drafts, in favour of James Martin, to the amount of 1000_l._, which he had purchased, taken from him.
He was, however, soon afterwards again discharged out of custody, the money being retained in the hands of the bankers.
In 1815 he resolved to recover the bills and drafts from the magistrates, by whom they had been taken from him; and as they refused compliance with his request by letters, he visited Glasgow in person, and demanded, in the most insolent manner, the restitution of what he called his property. This being refused, he commenced an action against them, which, more than any other case that ever came before a court of justice, proves the glorious uncertainty of the law; for it continued to be litigated for five years; and, the bankers having become the defendants, the country, for the first time, witnessed the singular fact of an acknowledged thief contending with persons for the property he had actually stolen from them.
During the progress of this protracted case, Mackcoull attended the courts of law in person, and gave instructions to his agent. He always conducted himself with the greatest _sang froid_, and treated with contempt and derision the allusions made by counsel to his character. At length it was ruled that Mackcoull should be interrogated in person before the court; and after some hesitation he consented. This circumstance was no sooner known, than crowds flocked to hear his examination, which lasted for several days. He behaved in the most cool and determined manner; and when his absurd replies elicited a laugh in court, he always smiled with seeming self-approbation. The account he gave of himself was that he traded as a merchant, and that he chiefly transacted business with one James Martin, whose residence he could not tell. He objected to many questions put to him with the acuteness of a lawyer, and at length the session rose without having come to any decision; and Mackcoull returned to London in great spirits, to arrange with his brother John with respect to his future proceedings.