A rogue tweet by his son taught Gordon Brown "a big lesson" about the need for parental supervision, he said today as he launched an online safety campaign, Sky News reported.

Children will be taught how to protect themselves online with the 21st century equivalent of the Green Cross Code's 'Stop, Look, Listen.'

Speaking at the formal unveiling of the U.K. Council for Child Internet Safety's first strategy, the Prime Minister said last week's intervention by younger son Fraser had shown him how important supervision was.

"Last week, the people who follow Sarah, my wife, on Twitter received a message of gobbledegook which my younger son had bashed out on the keys and then pressed send while she was out of the room," he told the audience.

"It started with our mistake and, of course, it was a mistake not to supervise the internet and we were taught a big lesson as a result of that."

Sarah Brown has over a million followers on the site who were surprised to see she had written: "fvdfzsrsazxzzxcvbnmadgfhjjkqwrtyuuuiop."

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