This looks like the article here:
http://www.timesonline.co.uk/article/0,,29389- 2187711,00.html
These sort of cases are difficult because if they're settled out of court there's often a confidentiality clause which means we never get to find out the true details.
There's some stuff about the inmate requiring long term medical care.
If for example a warder who was untrained in first aid tried to give heart massage or cut him down and this resulted in him sustaining a permanent injury like a broken back - this might be the sort of thing we're talking about because it's a large settlement.
In some countries there is a "good samaritan law" that means that people who try to help someone who's life is in danger cannot be held responsible for consequential injuries - maybe we need one of those