To coincide with the launch of a new book: Peace Inside: A Prisoners Guide to Meditation, its editor, Sam Settle, was interviewed on BBC 4's 'All in the Mind' here. The piece starts at 10.20 minutes into the programme.
More details on the book can be found here: http://www.jkp.com/uk/peace-inside-2.html
And the Prison Phoenix Trust (that I helped found) here: http://www.theppt.org.uk
The book is beautifully constructed and the explanation of how to meditate one of the clearest and simplest I have read necessarily so given it may be the only source of information a prison inmate might have at their disposal. But like any good account it is suitable for all - inside or out under any number of conditions of our 'imprisonment'!