The first story I read on this puff of smoke noted that the information was mostly in the public domain, and that there was no clear evidence that there was anything illegal about it. I believe it is just another phase in the Brit/NI govts' spin campaign to "manage" the facts of the Castlereagh event on St. Patrick's Day, where three men just walked into the supposedly most secure barracks in Europe, went directly to "room 220" (which had been physically relocated a few days previously), and walked out with top-secret files, far more detailed than the "public domain" materials now "discovered" on a computer taken from somebody's home. I doubt anyone but an ardent loyalist/unionist buys into it at any rational level, but even bald-faced lies develop a patina of respectibility if repeated often enough.