The discovery, indeed, of the infamous wretches and their intended diabolical act is next to a miracle, and is only to be attributed to the determination and perseverance of the man who made the communication to the earl of Harrowby: he called at his lordship’s house, in Grosvenor-square, on Wednesday morning, (the 23d), between eleven and twelve o’clock, and inquired of the porter if the noble earl was at home? The porter replied in the negative. The man appeared very anxious to see his lordship, but the porter did not give him any hopes, as he refused to tell his business; the man, however, urged the necessity of seeing his lordship, without loss of time; and at length he observed, that if he did not see him, the porter would not be sitting in his chair in the hall to-morrow. This observation astonished the porter, and induced him to believe that the man really had something of a serious and alarming nature to communicate to the noble earl: he then told him that his lordship was riding on horseback in the park, directed him to that part in which he was most likely to find him, and described his groom and the livery he wore, &c. The man hastened to the Park, and discovered the groom, as described by the porter, hailed him, and asked him if the gentleman before was the earl of Harrowby? The groom replied in the affirmative. The man then told him, that he wanted and must speak with his lordship. The groom informed his noble master, who immediately stopped his horse. The man then presented a letter to him, which the earl opened and read. The man having informed him that he had a deal more to communicate, his lordship dismounted, and walked and talked with the man for some time; and the result of their interview was the communication to the secretary of state, of which we have just spoken.

Precautions were immediately taken at the secretary of state’s office, for the discovery and apprehension of the villains. The first intimation that was given of the affair at the office in Bow-street was at past seven o’clock, when it was made known that a number of officers, constables, and patrol, would be wanted. Ellis, who is a conductor of a party of patrol, was ordered to leave his division, and repair to the office with the men under his direction. The expedition upon which they were to be sent was kept a secret till they started, which was between half-past eight o’clock and nine. The place of rendezvous of the assassins was in Cato-street, John-street, in the Edgware-road, where the neighbours had become alarmed by a number of strange men assembling in a stable, and a loft over it, after dark; sacks being hung up on the inside of the windows to prevent detection.

In the course of the day inquiries had been made, and the result was, that some desperate act was expected to take place. The ministers’ servants were armed with pistols, and two officers or constables appointed to each residence. The Earl of Harrowby and Viscount Castlereagh dined with the Earl of Liverpool; and at nine o’clock they went to the secretary of state’s office for the home department, at which time all the cabinet ministers assembled. Mr. Birnie, the magistrate, was directed by Viscount Sidmouth to be in Cato-street, and in readiness to act in case of emergency. A party of the guards, under the command of Captain Fitzclarence, was ordered to march to Cato-street, to assist the police, if necessary. Unfortunately, however, they were not clearly directed, or they did not understand where the place was, as they were at the contrary end of the street when the assassins commenced their murderous attack upon the officers, and it was only by the discharge of pistols that they found out where the building was. When the police-officers arrived, they found two sentinels at the door, armed with guns and swords. These opposed their admittance without the pass-word. The officers, however, soon overpowered and secured them. They then gave an alarm, and the officers heard by the noise in the loft that several persons were up stairs. They ascended to the loft by a ladder which the conspirators themselves had used; when the contest, which we have already described, ending in the arrest of most of the conspirators, took place.

The same sources of information which led to the detection of the conspiracy enabled the magistrates to trace the hiding-place of Thistlewood. Instead of returning to his own lodgings in Stanhope-street, Clare-market, it was discovered that he had proceeded to an obscure house, No. 8, White-street, Little Moorfields. Thither, at nine o’clock on Thursday morning, the 24th of February, Lavender, Bishop, Ruthven, Salmon, and six of the patrol, were despatched. On arriving at the house, three of the latter were placed at the front, and three at the back door, to prevent escape. Bishop observed a room on the ground-floor, the door of which he tried to open, but found it locked. He called to a woman in the opposite apartment, whose name is Harris, to fetch him the key. She hesitated, but at last brought it. He then opened the door softly. The light was partially excluded, from the shutters being shut; but he perceived a bed in the corner, and advanced. At that instant a head was gently raised from under the blankets, and the countenance of Thistlewood was presented to his view. Bishop drew a pistol, and presenting it at him, exclaimed, “Mr. Thistlewood, I am a Bow-street officer; you are my prisoner:” and then, “to make assurance doubly sure,” he threw himself upon him. Thistlewood said, he would make no resistance. Lavender, Ruthven, and Salmon, were then called, and the prisoner was permitted to rise. He had his breeches and stockings on, and seemed much agitated. On being dressed, he was handcuffed; in his pockets were found some ball-cartridges and flints, the black girdle, or belt, which he was seen to wear in Cato-street, and a sort of military silk sash.

A hackney-coach was then sent for, and he was conveyed to Bow-street. In his way thither he was asked by Bishop, what he meant to do with the ball-cartridges; he declined answering any questions. He was followed by a crowd of persons, who repeatedly cried out, “Hang the villain! hang the assassin!” and used other exclamations of a similar nature.

When he arrived at Bow-street, he was first taken into the public office, but subsequently into a private room, where he was heard, unguardedly, to say, that “he knew he had killed one man, and he only hoped it was Stafford;” meaning Mr. Stafford, the chief clerk of the office, to whose unremitting exertions in the detection of public delinquents too much praise cannot be given.

Mr. Birnie, having taken a short examination of the prisoner, sent him to Whitehall to be examined by the Privy-Council. Here the crowd was as great as that which had been collected in Bow-street. Persons of the highest rank came pouring into the Home Office, to learn the particulars of what had transpired.

The arrest of Thistlewood was heard with infinite satisfaction; he was placed in a room on the ground-floor, and a vast number of persons were admitted in their turn to see him. His appearance was most forbidding. His countenance, at all times unfavourable, seemed now to have acquired an additional degree of malignity. His dark eye turned upon the spectators as they came in, as if he expected to see some of his companions in guilt, who he had heard were to be brought thither. He drank some porter that was handed to him, and occasionally asked questions, principally as to the names of the persons who came to look at him. Then he asked “to what gaol he should be sent?—he hoped not to Horsham.” (This was the place in which he was confined, in consequence of his conviction for sending a challenge to Lord Sidmouth.)

At two o’clock he was conducted before the Privy-Council. He was still handcuffed, but mounted the stairs with alacrity. On entering the council-chamber he was placed at the foot of the table. He was then addressed by the Lord Chancellor, who informed him that he stood charged with the twofold crime of treason and murder; and asked him whether he had anything to say for himself? He answered, that “he should decline saying any thing on that occasion.”

No persons were suffered to have access except those on business to the public offices at Whitehall, nor was any individual allowed to hold communication with the prisoner. About a dozen soldiers were in the hall and adjoining lodge; they formed a part of the military escort that accompanied the police-officers to the spot where Thistlewood and his companions were first discovered. The soldiers had with them the different articles and weapons found upon the party when taken, among which were two small pistols, one of them loaded, and a bundle of files, similar to those used in small brasswork. The points of such files are always sharp, and the part of the file which goes into the handle is necessarily pointed, to penetrate the hole made in the wood for its reception; some of the files appeared, however, to have had the handle-points brightened, and the ends made more fine, as if by being whetted upon a stone. There were also in the hall two or three bags, containing three bayonets and some ammunition, made up in both small and large cartridges. The soldiers who had seized those articles were examined before the Privy-Council. After his examination, Thistlewood was taken back to the room in which he had been previously placed; his commitment to Coldbath-fields was made out, and he was conveyed to that prison under the care of six officers. There was a partial shouting and groaning, as the carriage in which he was placed drove off.