It was alleged last night that Mr Cleary was online in the middle of hacking when he was held. The arrest came hours after an anonymous internet user claiming to be from LulzSec threatened to publish the entire 2011 census database, though this was later dismissed as a hoax. A Scotland Yard spokesman said a “significant amount of material” had been seized from Mr Cleary’s family home by officers from its specialist e-crime unit, and would now be subjected to forensic examination.