Armed officers were poised to swoop as Williams was performing an encore during his show last June.
However, organisers of the gig realised the potential suspects may have been plain clothes security guards hired by Williams to deter bootleg merchandise sellers. The alert was stood down when they were able to show their official accreditation.
The drama unfolded in the police control area at Murrayfield at the climax of a concert, staged just days after the bomb attack at an Ariana Grande concert in Manchester, which claimed 23 lives.
Speaking at an events conference in Glasgow yesterday, Colin Rodger, head of event management at DF Concerts, said he feared the worst when he noticed growing police activity as the concert drew to a close.
He said: “I had decided, due to the climate at the time, that I would base myself in the police control room to make sure that the event went well.
“Right at the end, when Robbie was performing his encore, I saw the police all watching the cameras fervently. They were focused on these guys standing on street corners.
“Suddenly, after every bit of planning we had done about profiling people and people acting suspiciously, we had a real incident on our hands.
“We had people on four street corners who fitted the bill. Nobody knew who they were. The alarmed police started to move in. It was a very, very wobbly movement in the control moment. I suddenly had a flash of inspiration that they could be the merchandisers’ security guys. Luckily we had accredited them.”