The World Prison Brief at PrisonStudies.org is an online database providing free access to information on prison systems around the world. It is now hosted by the Institute For Crime & Justice Policy Research (ICPR), Birkbeck College, University of London.
It was previously hosted by the International Centre for Prison Studies (ICPS). It was a research centre at the University of Essex. It was launched at the House of Lords on 4 April 2011. Between 1997 and 2010 ICPS was based in King's College London and was launched formally by Home Secretary Jack Straw in October 1997. In July 2010 the International Centre for Prison Studies incorporated and registered as a charity with the Charities Commission of England and Wales. From the outset the Centre was independent of governmental and intergovernmental agencies, although it would work closely with them.
So who really knows what the quality of the data is without further investigation. But it seems to have been originally created by the UK’s military-intelligence-industrial complex.