The Leveson Inquiry has heard from senior officers investigating corruption in the police force today.DCI Brendan Gilmour, who worked on Operation Glade, investigating police corruption from 2002 to 2005, said seven journalists were interviewed under caution in 2004 after evidence suggested they had been commissioning private investigators to obtain information illegally.The officer said all of the journalists – two working for the News of the World, one for the Mirror, one for the Sunday Mirror, one for the Mail on Sunday and two freelancers – had said they would not have used private investigator Steve Whittamore, or other agencies, if they had known how information had been accessed.He said there was clear evidence that civilian employee Paul Marshall was providing information from the police national computer to private investigators at the request of a number of reporters.He added: “It was put to the journalists that the speed with which the checks were being turned around would suggest they weren’t being obtained through the courts or court records but that said we couldn’t establish guilty knowledge of the part of the journalists as to where that information was coming from.”Robert Jay QC, inquiry counsel, pointed out the journalists were sent written invitations to attend places to be interviewed under caution, and had legal advice, meaning answers could have been orchestrated in advance.In March 2004, the Crown Prosecution Service advised there was insufficient evidence to charge any of the journalists.Gilmour told the inquiry: “I accepted the decision on the basis that we couldn’t prove guilty knowledge. I wasn’t disappointed with the CPS taking that decision; I was disappointed that we couldn’t prove guilty knowledge.”Russell Middleton, an acting chief constable and deputy senior investigating officer on Operation Reproof, examining corruption at Devon and Cornwall police, said he had discovered a flow of information from an officer to a private investigator, who then passed it on to various companies.He added the police never found evidence of requests from journalists, but it would have been included in the scope of the inquiry.37 people were investigated under Reproof, and two serving police officer, two former officers and two private investigators were charged in 2004. Middleton said two senior politicians had been named in the evidence retrieved.David Sherbone, counsel for the victims at the inquiry, requested that he be able to address Gimour’s evidence later this afternoon.