Good Morning Britain hosts Kate Garraway and Richard Madeley have apologised to viewers after veteran foreign correspondent John Simpson swore live on air shortly before 7am.

The 76-year-old appeared on the ITV show to discuss his recent novel Our Friends In Beijing and recalled when he had experienced a mock execution while working in Beirut, Lebanon.

Simpson said the protagonist in the book both “is me and it isn’t” and that about 80% of the events featured had either happened to him or people close to him during their careers as foreign correspondents.

After Madeley asked whether a mock execution detailed in the book was based on real life, Simpson said: “It was me in Beirut some years ago and I was made to kneel down.

“A guy stuck a gun in the back of my neck and pulled the trigger and I thought my last moment had come.

“And then everybody laughed and I got up and I brushed off my knees and I thought, ‘I’ve got to reassert myself here’.

“So I said to the guy who had fired the gun, or hadn’t fired the gun, ‘Do you know what? You’re a real wanker’.”

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Kate Garraway (Ian West/PA)

Simpson held his hands up then covered his mouth after realising his mistake.

Garraway joked he was “also in trouble now for saying that on breakfast television”.

She added: “We won’t give you a mock execution. You are OK John, you are OK.”

Madeley, one of the guest presenters drafted in following Piers Morgan’s departure in March, apologised to viewers but added: “You were talking about something utterly fundamental.”