Five or six years later, William Roupell minutely described how he had effected the fraud. The day his father died he got the keys of his private bureau, opened it, and took out the authentic will. After reading it, and finding this unfavourable to himself, he resolved to carry out his deliberate plan, namely, to suppress it and substitute another. He himself prepared it on a blank form which he had brought with him on purpose. To this fraudulent instrument he appended forged signatures, and in due course obtained probate. As he possessed nearly unbounded influence over his mother, her accession to the property meant that William could dispose of it as he pleased. He embarked forthwith in a career of the wildest extravagance, and ere long he had parted in his mother's name with most of the landed estates. One large item of his expenditure was a contested election at Lambeth, which he gained at a cost of £10,000. No fortune could stand the inroads he made into his mother's money, and in 1862 he was obliged to fly the country, hopelessly and irretrievably ruined.
His disappearance gave colour and substance to evil reports already in circulation that the will and conveyance above referred to were fictitious documents. His next brother, who should have inherited under the authentic will, forthwith brought an ejectment on the possessor of lands purchased on the authority of the forged conveyance and will. The case was tried at Guildford Assizes, and caused intense excitement, the hardship to the holders of these lands being plain, should the allegations of invalidity be made good. The effect of establishing the forgeries would be to restore to the Roupell family lands for which a price had already been paid in all good faith to another, but a criminal member of the family. At first the case was contested hotly, but, to the profound astonishment of every one inside and outside the court, William Roupell himself was brought as a principal witness to clench the case by a confession altogether against himself. He told his story with perfect coolness and self-possession, but in a grave and serious tone. "Every word he uttered was said with consideration, and sometimes with a long pause, but at the same time with an air of the most entire truthfulness and candour." He confessed himself a perjurer in having sworn to the false will, and a wholesale forger, having manufactured no less than ten false signatures to deeds involving on the whole some £350,000.