A full background check was carried out and the programme resumed shortly afterwards, when the King and Queen conducted a jovial walkabout in the sunshine outside the hotel.
Stall holders claimed the threat concerned a drone but the rumour was said to be unfounded.
Matt Taylor, founder of Jersey Sea Salt, was chatting to the King when he was approached by his protection officer and told he had to leave immediately.
He said: “He stopped at the stall and said ‘Ooh sea salt’ and I said ‘Come and have a chat, Sir.’
“Then his security appeared and grabbed me and said ‘He has to go, now’.
“He didn’t seem panicked but he was quite stern. They just ushered him out. It’s a shame as he’d stopped to chat to us of his own accord.”
Eamon Fenlon, managing director of Jersey Dairy, had just served the Queen an ice cream from a van before she was ushered out of the Expo.
Mr Fenlon said: “I had just given the Queen an ice cream and I turned back to get one myself before we had a chat.
“But when I turned back round she had been whisked off. Some of the other people told me it was a drone but whether that’s official or not I don’t know.”