Carefully concealed about his person, he had a couple of small files, and setting to work with these implements, he so nearly cut through the bars, that he could immediately remove them when needful. The main difficulty was now overcome, but the windows were at a considerable height from the ground; and, moreover, there were sentinels both at the back and front, who must be eluded before an escape could be effected. The Earl of Wintoun, however, was confident in his own ability to manage the matter, and did not doubt he should find an opportunity of getting off. The opportunity occurred. During the day a fog had prevailed in the City, and of course extended to the Tower. Indeed, it was thicker there than elsewhere. Towards night the vapour increased in density. Not only was the White Tower completely hidden, but all the surrounding buildings were obscured. The sentinels could scarcely be distinguished on their posts. Links were lighted, but only served to make the darkness more palpable. When the fog first came on, the Earl of Wintoun resolved to take advantage of the chance thus offered him, but he waited patiently till night. No extra precaution seemed to be taken by the jailers, except that the entrance to the Hall Tower from the inner ward was fastened, but this mattered little, since the fugitive proposed to descend from the window looking towards the outer ward. No sooner had the jailer paid his last visit for the night than the earl removed the bars from the window, tied a couple of sheets together and fastened them, and then listened intently for the sound of the sentinel's footsteps, who was pacing to and fro beneath. So dark was it that Lord Wintoun could not see the man, but he could hear him, and when he judged by the sound that the sentinel was at the greatest distance, he let himself down as quickly and noiselessly as he could. A sound reached the man's ear, for he suddenly halted and called out: “Who goes there?” But receiving no answer, and hearing no further noise, he did not think it needful to give the alarm. Meanwhile, the Earl of Wintoun, who had remained perfectly quiet at this critical juncture, now stole to the further side of the ward, and crept along the edge of the wall till he got within a short distance of the Gate Tower. Here fortune favoured him. At the very moment of his arrival, a warder who had just come from the guard-room was opening the wicket to let out some half-dozen persons. Without hesitation, the earl mixed with the party, and though a link was brought, he escaped without attracting the warder's attention. But another portal had still to be passed at the opposite side of the bridge, and as Lord Wintoun was marching towards it with his companions, he felt his arm grasped, while a voice whispered in his ear: “You are one of the rebel lords. Your life is worth a thousand pounds. I must have that sum, or I will prevent your escape.”