William Roper was startled, indeed, to hear of the murder, and then bitterly annoyed. All the while on his rounds he had been congratulating himself on his coming promotion, and reckoning up the many advantages which would accrue from it, not the least of which was a wider prospect of finding a wife. The cup was dashed from his lips. He had acquired no merit in the eyes of the new Lord Loudwater, and he had most probably made the present Lady Loudwater his enemy, if the murdered man had divulged the source of his knowledge of her goings-on with Colonel Grey. He ate his mixed meal very sulkily, listening to the constable's account of the circumstances of the crime. Slowly, however, his face grew brighter as he listened; the new information he had obtained for his murdered employer might very well have an important bearing on the crime itself. He might yet establish himself as the benefactor of the family. On the way to the Castle he was so mysterious with Robert Black that the stout constable became a prey to mingled curiosity and doubt. He could not make up his mind whether William Roper really knew something of importance or was merely vapouring. William Roper neither gratified his curiosity, nor banished his doubt. He was alive to the advantage of reserving his information for the most important ear, so as to gain the greatest possible credit for it. At the first sight of him Mr. Flexen felt that he had before him an important witness, for he took a violent dislike to him, and he had observed, in the course of his many years' experience in the detection of crime, that the most important witness in hounding down a criminal was very often of a repulsive type, the nark type. William Roper was of that type, but his story was indeed startling. He first told how he had seen Colonel Grey kiss Lady Loudwater in the afternoon--Mr. Flexen noted that Lord Loudwater had accused her of kissing Grey--and of their spending most of the afternoon in the pavilion in the East wood. The time of his watching had already lengthened in William Roper's memory. There was nothing new in these facts, and Mr. Flexen saw no reason to suppose that they had any bearing on the crime. But William Roper went on to say that soon after ten in the evening he had been on his round in the East wood, when he saw Colonel Grey walking in the direction of the Castle. His curiosity had been aroused by what he had seen in the afternoon, and thinking it not unlikely that he was on his way to another meeting with the Lady Loudwater, and that it was the duty of a faithful retainer to make sure about it, with a view to informing his master should his surmise prove correct, he followed him. The Colonel went straight through the wood into the Castle garden, walked round the Castle, keeping in its shadow as he went, till he stood under the window of Lady Loudwater's suite of rooms.