Bentham remained bitter throughout his later life about the rejection of the Panopticon scheme, convinced that it had been thwarted by the King and an aristocratic elite.
It was largely because of his sense of injustice that he developed his ideas of "sinister interest"—that is, of the vested interests of the powerful conspiring against a wider public interest—which underpinned many of his broader arguments for reform.
He supplemented the supervisory principle with the idea of contract management; that is, an administration by contract as opposed to trust, where the director would have a pecuniary interest in lowering the average rate of mortality.
One station in the inspection part affording the most perfect view of every cell.
The architecture incorporates a tower central to a circular building that is divided into cells, each cell extending the entire thickness of the building to allow inner and outer windows.
The closest (circular and with a panoptic tower) are: the buildings of the now-closed Presidio Modelo in Cuba (constructed 1926–28); Pavilhão de Segurança, 1896, architect José Maria Nepomuceno, now part of an Outsider Art and Science museum, in Miguel Bombarda Hospital, Lisbon, Portugal (national monument); Autun penitentiary, France; Breda and Arnhem penitentiaries, 1884, architect Johan Frederik Metzlaar, Netherlands; Haarlem penitentiary, 1901, Netherlands; Stateville Penitentiary, 1919, Illinois, USA, architect C. Although most prison designs have included elements of surveillance, the essential elements of Bentham's design were not only that the custodians should be able to view the prisoners at all times (including times when they were in their cells), but also that the prisoners should be unable to see the custodians, and so could never be sure whether or not they were under surveillance.
This objective was extremely difficult to achieve within the constraints of the available technology, which explains why Bentham spent so many years reworking his plans.