It was at the height of Beatlemania, and Roberts, a radio reporter, was in the thick of it.
"Girls screaming, girls fainting, people throwing things -- you couldn't hear anything," he said.
Roberts has countless pictures of himself sitting a stone's throw away from John, Ringo, Paul and George.
"I was sitting there, had my microphone on the desk, was face-to-face, this close," he said.
During the news conference, he asked Lennon a question and got the musician's first statement on his controversial remark.
Larry Roberts: 'This one's for John, what question do you dislike being asked the most?"
John Lennon: "At the moment, the question, the one they're all asking, when we first get in, about the statement I made."
Larry Roberts: "Can you tell us about that?"
John Lennon: "Well, you ask me what you want to know, and I'll tell you. I'm not just going to go over and over it."
Decades later, Roberts was shocked to find out Bonhams & Butterfields in California was auctioning off the "only" copy of the news conference.
"Well, it's not the only copy now, folks," he said.
Roberts said he was shocked because he has the original.
"(I) tried to sell them in 1966, and nobody was interested, so I put the tape away," he said. "I kept it, and I kept it in really good condition. And when I saw this thing on the Internet about it being worth about $20,000 to $30,000, I'm going, 'What?' My tape and my voice."
Now he's hoping to cash in himself.
"I hope to get $10,000 out of it," he said with a laugh.
Even if his tattered box and weathered reel are long gone, the memories will never be forgotten, he said.
"It's become more important to me now since this has happened," Roberts said. "I didn't know what I had. (I) had no idea where it was going to go and, frankly, I've never seen anything like it since, and I don't think we ever will."
Roberts e-mailed Bonhams & Butterfields about his copy of the recording. The auction house told him it would get back to him after it auctioned off their copy.