The site at Millbank was originally purchased in 1799 from the Marquess of Salisbury for £12,000 by the philosopher Jeremy Bentham, acting on behalf of the Crown, for the erection of his proposed panopticon prison as Britain's new National Penitentiary. After various changes in circumstance, the Panopticon plan was abandoned in 1812. Proposals for the National Penitentiary continued, however, and were given a legislative basis in the Penitentiary House, etc. Act of 1812 (52 Geo. 3 c. 44). An architectural competition for a new prison building on the Millbank site attracted 43 entrants: the winning design was that of William Williams, drawing master at the Royal Military College, Sandhurst. Williams' basic plan was adapted by a practising architect, Thomas Hardwick, who began construction in the same year.