'You're a very naughty billionaire,' the attacker said

The man in the chequered shirt pushed past me just as Louise Mensch was finishing her question. In his hand was a blue carrier bag. He looked like he was trying to leave in a hurry.

Then someone screamed. I looked round a saw a paper party plate heaped with shaving foam from the bag which he was smearing across Rupert Murdoch face and suit a couple of yards away.

“You are a very naughty billionaire,” he said.

Rupert just sat there not moving. Not saying anything.

A slightly portly policeman started running across from the far side of the room but he was no match for Wendi Murdoch.

Sitting just behind her husband she instinctively leapt up and lunged at the man’s face – making contact with some papers she had in her hand.

Another aide tried to grab him before the policeman even made it to Mr Murdoch’s side.

As the attacker was led away Mrs Murdoch turned to her husband and his son. “I got him,” she said - almost gleefully.

Rather tenderly she then perched on the committee room table in front of Mr Murdoch, removed his glasses which were smeared with foam and tried to clean his face and bald head with a handkerchief and a bottle of mineral water.

Rupert himself still said nothing.

Whether he was shocked, upset you couldn’t really tell. He looked vulnerable – less the multi-billionaire media mogul and more the 80–year-old man.

His son, however, was angry. As officials tried to clear the room of the press and public he demanded of the nearest policeman – his own face covered in foam - how the man had got past security.

“Unfortunately the X-ray machines don’t pick up foam,” was the slightly lame reply.

“This is a circus,” James Murdoch replied. “Honestly, this is a circus.”

Another aide – mistaking me for a committee official – demanded to know if the cameras were off.

James then demanded an adjournment. But surprisingly his father, now with his foam-smeared suit jacket removed and wet shirt revealing his vest underneath was the one who was keen to continue.

“It’s fine. Let carry on.” I was then ushered out.

Even at close quarters Rupert’s reaction was inscrutable. At first I thought he was shocked. But now I am not so sure. It was almost as if he welcomed the ritual humiliation.