That's in line with what I expected, thanks. Specifically to read:
"Of the 15 individuals served, 11 did not comply with the notices. Of the 11, seven were charged and two convicted."
Whilst they may have been incarcerated since the report, at the least it would seem that there is some evidence based procedure to determine "guilt" in terms of whether you are able to produce the key or not.
http://www.bbc.co.uk/news/uk-england-11479831
http://www.theregister.co.uk/2009/08/11/ripa_iii_figures/