The prisons are Belmarsh, Brixton, Coldingley, Feltham, High Down, Pentonville, Wandsworth and Wormwood Scrubs.

BBC: Male prison assaults 'rise by a third' in London

"It's a very difficult environment in an old building in which to try to make the kind of changes Pentonville needs, " Ms Owers said.

BBC: NEWS | UK | Prison damned as 'vermin-ridden'

Mr Collins told the Court of Session in Edinburgh that the amount of cell space allocated to an inmate was apparently half that available to a prisoner at Pentonville jail in 1841.

BBC: Prisoner wins slopping out move