 While Mitford was helping Bridget Perceval place letters in the newspapers he was hidden away in Warburton's private asylum in Hoxton, Whitmore House.In the spring of 1813 Bridget Perceval and Mitford 'overleaped the bounds the prudence' and a letter in "The News" purportedly signed by Lords Eldon, Castlereagh, and Liverpool and promising Caroline a larger establishment was traced to Mitford, who swore that the letter had originated with Lady Perceval and that he had no idea it was a forgery.Lady Perceval denied all knowledge of the letter and brought a case against Mitford for perjury; Mitford was tried and acquitted.