Unprintable tales of explosive scandals involving politicians and celebrities were stored in a "Wild West-style" safe in the Sun's newsroom if they could not be used, a court heard.
The tabloid's former deputy news editor Ben O'Driscoll, 38, said more than 30 years of unpublished stories were stored in the 7ft high safe.
He told Kingston Crown Court the paper kept hold of "eye-popping" reports, pictures, and videos which had not made the paper because they were not in the public interest.
"At the time I was there, there was an enormous safe, about 7ft high, like something out of a Wild West film, with big metal handles", he said.
"It was full of 30 years of stories that are confidential and did not pass the public interest test.
"They remained there in that safe, and what's in there is quite eye-popping, I have to say."
He said MPs and celebrities feature in the material, joking: "If you were to publish everything in that safe, I think The Sun's circulation figures would go upwards."
O'Driscoll is on trial accused of conspiracy to commit misconduct in public office by paying PC Simon Quinn, another serving police officer and Broadmoor healthcare assistant Robert Neave for stories that were published in The Sun.
He is in the dock with The Sun's former managing editor Graham Dudman, 51, head of news Chris Pharo, 45, reporters John Troup, 49, and Jamie Pyatt, 51, and picture editor John Edwards, 50, who all face similar corruption charges.
He said he dealt with more than 300 emails each day in an atmosphere of "information overload", and would have to sift through more than 1,000 stories to find the most newsworthy tales.
O'Driscoll agreed The Sun newsroom was "like a caldron", with little time to consider decisions he was making.
"As well as emails and phone calls, there were angry editors and angry sub-editors, the pressure was building, and you also had a queue of reporters behind your desk waiting to speak to you", he said.
"There was never a moment, it was speed of thought and you had to make decisions."
O'Driscoll said he was responsible for "pricing" payments to sources in Pharo's absence, based on where they were placed in the paper.
"If Mr Pharo wasn't there, it would fall to me to price those stories", he said.
"They are priced at £750 if they are towards the front and £500 if they are towards the back (of the paper)."
Pyatt gave evidence yesterday that O'Driscoll and Pharo both knew he had paid sources who were public officials, and said he kept them both informed of his meetings with Robert Neave and Simon Quinn.
But O'Driscoll told the court: "It pains me greatly, but Mr Pyatt was not telling the truth.
"Mr Pyatt said yesterday he told the news desk when he was meeting public officials and was updating us of those meetings.
"He said he kept us updated on every story he was working on that involved a public official."
Martin Hicks QC, defending, asked: "Would you receive any calls of that nature from him?"
O'Driscoll replied: "Never."
He said he was "sceptical" of Pyatt's claims to have good sources, and took little in his emails at face value.
Asked about source boosting, O'Driscoll said: "I wasn't familiar with that term but I was very family with that practice – to inflate the level of your source to make it sound like you have got very good sources.
"Quite often someone has one source but they make it look like four or five to make it appear that they are better connected than they are."
O'Driscoll said all stories were judged on whether they were in the public interest, and the editor would make the final decision on big stories.
He said payments were all made after stories had been published, with only certain notable exceptions when that was not possible.
He said editor Rebekah Brooks had once handed him a case with £20,000 in cash when the chance to buy footage of a friendly fire military incident came up.
"I was running the desk, we had a call about it and it was obviously of huge importance", he said.
"I went to Rebekah Brooks, I told her of the story, and the public interest behind it, that we needed £20,000 in cash there and then to give to the reporter.
"She gave me a case of money and the reporter went to get the footage."
O'Driscoll, who is married with two young sons, started his working life as the Ascot reporter at the Windsor and Eton Express.
He joined INS news agency in 2002, took on casual shifts at The Sun in early 2003, before joining the paper full time as assistant news editor in 2004.
O'Driscoll was promoted to deputy news editor in 2006, working under news editor Pharo, and left the paper in January 2011 to become deputy news editor at the Daily Mail.
He said unlike other defendants, the Daily Mail did not suspend him and he worked up to the start of the trial.
Earlier, the court was read character references for Pyatt, hailing his integrity and work as a journalist.
Trevor Foster, whose daughter Hannah was murdered in 2003, praised Pyatt for helping bring her killer to justice.
Pyatt flew to India to help the search for the murderer, keeping the Foster family informed of developments and advising them to make a public appeal for information.
He said he remembers the moment the killer was convicted, seeing Pyatt welling up in court before giving him a "thumbs up" sign.
"The man is genuine, the man has integrity, the man has my trust, and I will always have him on my team", said Foster.
Wendy Downing, the treasurer of the residents association that Pyatt chairs, described him as "a man of true integrity, loyalty, and honesty".
She said: "He is a man I am proud to have as a friend and chairman of our residents association."