By Martin Hickman.Rebekah Brooks would have had to have been a "complete fool" not to suspect that a Sun journalist's "No 1 military contact" was a public official, prosecutor Andrew Edis QC told the phone hacking trial today.Mr Edis suggested it was obvious that stories appearing in the Sun were coming from a public servant rather than "a retired general in a bathchair in Eastbourne or a "someone in a pub in Aldershot."Mrs Brooks is accusing of conspiring to commit misconduct in public office by authorising £40,000 of cash payments between 2006 and 2009 to a source who turned out to be a Ministry of Defence official, Bettina Jordan Barber.After receiving 11 emails from the journalist referring to the exclusives provided by his source, Mrs Brooks agreed the payments.In her evidence, she said it had never occurred to her that the source might be a public official because she trusted the journalist, and did not believe that such an experienced professional journalist would ever do such a thing.Making the second day of his closing speech, Mr Edis told the jury that the nature of the stories - among them detailed accounts of military disciplinary cases and Army tragedies from Iraq to Afghanistan - made it plain that the source was always right, well-connected and in the military.He said: "In order to be acquitted of this count, you are going to have to be in the state of mind - because she is entitled to the benefit of the doubt - that she must have been a complete fool. But she isn't, is she?"He went on: "Her case has to be that: 'It never occurred to me that this person might have been a public official'."Well, what sort of idiot would you have to be, over that period of time, to say it didn't occur to me?"If the thought had occurred to Mrs Brooks, Mr Edis told the jury, "she would have had to investigate, wouldn't she?"And she could have done so, he said, because the cash payments were made via Thomas Cook branches and the person receiving them had to establish their identity at the counter of the travel agency - which meant the Sun's financial department had to know the identity of the recipient.But despite telling the Press Complaints Commission that cash payments were policed, the reality was that Mrs Brooks was acting as a "rubber stamp," the prosecutor told the Old Bailey.Mr Edis said: "The fact of the matter is that the material that is relevant on this count clearly raises in the mind of intelligent person that the paper was paying a public official: which indeed it was."Mrs Brooks, who edited the Sun between 2003 and 2009, denies conspiring to commit misconduct in a public office, conspiracy to hack phones and conspiracy to pervert the course of justice. The jury will not sit in the case tomorrow and it is due to resume on Monday.