His fortunes, like those of more celebrated individuals, were precarious; and after various successes and disappointments, in his twenty-eighth year he married the mistress of a brothel, and assisted her in furnishing her house in Clifford's Inn Passage, which, in addition to its being a receptacle for unfortunate women, he made a depot for stolen property. He was not destined to remain long unknown in his new avocation, however; and his secret depository having been discovered, he was compelled to quit London to avoid his being taken into custody. He subsequently, in 1802, went to Germany, where he passed as an English merchant named Moffat; but being compelled to have recourse to his original trade of picking pockets, as the only means of obtaining a living, he was suspected and at length, in 1805, after having visited most of the continental towns, was obliged to make a precipitate retreat home again. London, however, he soon found was no stage for him to act upon, and he proceeded to Scotland, where for a long time he carried on his "profession" under the mask of his being a leather-seller. The idea of the possibility of the robbery of the Scotch bank having struck him, it was carried out, with the aid of White and a man named French, in the manner which we have already detailed; and having by his ingenuity succeeded in securing his own safety, as well as the possession of 8000_l._ of the stolen money, he retired into private life. By many it was supposed that he was now gone to the West Indies; but, in fact, he was industriously employed in Scotland in passing the notes of which he had retained possession. In 1812 he again visited London, but having broken faith with the bank in retaining the 8000_l._, he was apprehended and sent to Glasgow, where he arrived on the 8th of April 1812, and was committed to jail. While here he did not seriously deny the robbery, but offered to make restitution to the bank, and promised their agent 1000_l._, and gave them a bill for 400_l._ The bank not being at this time prepared to substantiate his guilt, he was discharged in the following July, and the agent of the bankers absolutely received from Mr. Harmer, of London the 1000_l._, which however Mackcoull subsequently recovered by suit at law from that able solicitor, he having paid it without sufficient authority. 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.