DURING the 12 years he spent locked up for murder, Jason Warr was shunted between various prisons. The Victorian jails were particularly grim. Arriving at Reading prison, Mr Warr (who has always protested his innocence) was greeted with rubbish thrown from high windows. Inside, the heating and plumbing were erratic and insects and vermin were common. After years soaked in filth, blood and fear, the prison stank.

The large, oppressive prisons built in Britain in the 19th century have long been thought inadequate. Cells are stacked in rows either side of a narrow central atrium—inevitably now covered with netting to prevent prisoners flinging themselves or others to their deaths. A damning report on the Victorian-era Pentonville prison (pictured) published on February 18th described infestations of mice and cockroaches and poorly ventilated cells. Reading’s prison closed at the end of last year. But, oddly, Victorian prison design is coming back.

The layout of Thameside, a privately run prison that opened in 2012, mirrors that of the loathed Pentonville. Wings on the main block radiate out from a central point: seen from the air, it resembles an asterisk. The interior is distinctly Victorian, too. Each four-storey wing is divided laterally in half into two-storey sections, within which cells are arranged around central atriums. Other new prisons are as big or bigger than the Victorian behemoths. Oakwood holds more than 1,600 inmates. Building will start in the summer on a new prison in Wrexham, in Wales, which will hold more than 2,000.

One reason for the Victorian revival is that other designs have proved even worse. Prisons built in the 1960s and 1970s resemble hospitals. Ceilings are low, allowing prisoners to scratch the lenses of CCTV cameras or yank off their metal cases to use as weapons. Small corridors contain dangerous blind spots. During riots in Risley prison, which opened in 1964, people were trapped on landings where stairwells stopped halfway down. Control is simply easier in older prisons, says Kevin Lockyer, a former governor. Better lines of sight mean fewer staff are needed on wings, making them cheaper to run.

Some of the grimness of the 19th century has been alleviated in the new prisons. Soft vinyl flooring and acoustic panels reduce the racket from slammed doors and bellowing prisoners. Insulation and heating are better: underfloor heating is replacing radiators and pipes, since the latter can be used as weapons in riots. The electric plumbing in cells can be controlled from outside. Taps stop running after ten seconds, making it harder to block sinks and toilets; waste pipes widen as they descend for the same reason.

Not everything is better in the new prisons. Thicker insulation can make prisons stifling in summer. Communal dining rooms—a feature, albeit often unused, of mid-20th-century prisons—are increasingly rare. Cost seems to be the reason: it takes a lot of officers to control them, compared with having prisoners eat in their cells. As a consequence, inmates have fewer opportunities to socialise normally.

In any case, good architecture is not enough. In their report on Oakwood last June, inspectors commended its impressive environment and accommodation. On other measures it was judged dreadful. Design makes little difference if people are locked in their cells all day, points out David Wilson, a criminologist at Birmingham City University and a former prison governor. What happens, or does not happen, within the walls of prisons matters even more than the walls themselves.