As has already been pointed out Orderlimit,
1) There's vast differences between different catagory prisons and
2) There's a huge difference between what is supposed to happen and what really does happen and 23 hour lockups are more common than the prison service would have us believe.
Its been a long time since I read this book
http://www.amazon.co.uk/Prisongate-Shocking-Britains-Prisons-Visionary/dp/0743259521
but I seem to remember David Ramsbotham talking at length about the amount of time prisoners were kept caged up. Treat people like animals and you will get??? Any guesses?
Also cat A prisons are lifer prisons and tend to be run (by there very nature) different than the normal prison regime. Ive never had the chance to cook my own meals in clink.