This has happened before, although the details aren't clear. It was reported last year (http://www.theregister.co.uk/2009/08/11/ripa_iii_figures/) that two people had been convicted for similar offences. It seems that most people don't comply, but not all of them are charged: "Of the 15 individuals served, 11 did not comply with the notices. Of the 11, seven were charged and two convicted."