Mr Evans said that at a meeting at South Mimms Service Station the night before Lewis’s arrest, Mr Landsman, his brother Adam and fellow director Dan Risner had agreed to report the matter.
Under cross examination, staff members had agreed that before the police arrived Lewis had been moved from duties directly involving children at the camp.
The court heard that Mr Landsman was of good character and had no previous convictions or cautions.
A character witness, Ilan Ben-Zion, who is a trainee clinical psychologist, described Mr Landsman as "extremely bright, vibrant, enthusiastic and determined".
Mr Ben-Zion said: "He loves spending time with children and has the utmost respect for them."
Earlier, the jury of seven men and five women had heard from a member staff, Sandra Vicente, that the sight of the images on Lewis's phone had "polluted" her brain.
Ms Vicente said Lewis had given her his phone and PIN so she could play music at a children's party on 1 August last year.
She said the images were also seen by two other workers, Mohammed Ramli and Shelby Silver.
That night she said she told Mr Landsman what she had seen, but the prosecution allege he did nothing, and allowed his friend to continue at work.
Ms Vicente said the next day Lewis spoke to her at work. "He said: 'There is something disgusting on my phone. I don't know how it got there,'" she said.
Three days later she reported Lewis to the police.
Mr Landsman, of Crambus Court, Admiral Drive, Stevenage, pleads not guilty to a single charge of cruelty to a person under 16 between 31 July and 7 August 2015.
Prosecutor Ann Evans told the jury: "You may think this is the height of irresponsibility and, as co-owner, his first duty in this situation should have been to the children, not the co-owner Ben Lewis. He said he would write a report about what happened and she trusted him to do so. He even suggested to Sandra that it might just be a phase Ben was going through."
Mrs Evans said staff had immediately told Tal Landsman what had been found on Lewis's phone. She said: "In an effort to protect his friend he did nothing about what he had heard, and allowed the parties and activities to keep running at the camp until eventually Ofsted moved in and closed the place down on August 6 last year.
"As far as Mr Landsman is concerned, friend or no friend, it was his obligation for the safety of the children in his care to report Mr Lewis, to remove him from the premises, or shut the operations. By not doing so he exposed these children to the unnecessary risk that they would suffer harm at the hands of his co-director."
The jury has been told Lewis, 26, formerly of Lullington Garth, Borehamwood had earlier pleaded guilty to three counts of making (downloading) indecent photographs of a child and one of taking an indecent photograph of a child.
The case continues.
