Ex-News of the World editor Colin Myler has said he feared \"bombs under the newsroom floor\" in the form of possible widespread wrongdoing in the past.He \"always had some discomfort\", but accepted phone hacking must have been limited because police had not shown otherwise, he told the Leveson Inquiry.Mr Myler took the job in 2007, after a reporter and private investigator had been jailed for phone hacking.A former NoW reporter and a private detective are also giving evidence.Reporter Daniel Sanderson and investigator Derek Webb, who carried out surveillance for the NoW on lawyers representing phone-hacking victims, are appearing at the Royal Courts of Justice in London on Thursday.Mr Myler took over running the paper in January 2007, after royal editor Clive Goodman and private investigator Glenn Mulcaire were jailed for illegally accessing the voicemails of royal aides.Giving evidence for a second day on Thursday morning, Mr Myler said he had initially believed News International\'s assertion that phone hacking at NoW had been limited to \"one rogue reporter\".\"Given what I believed to be a thorough police investigation throughout that period, and the fact that the police had not interviewed any other member of staff from the News of the World other than Mr Goodman, I think that weighed heavily on my mind,\" Mr Myler said.\"I assumed that they would have done so if they had any kind of evidence or reason to speak to somebody else.\"