The driver of the boat, Matthew Gibson, had no UK-recognised qualification despite having five years' experience as a ski-boat driver. Staff said there was a "lax" attitude to health and safety.
The court was told how parents of some of the children were watching from picnic tables when Mari-Simon fell into the water. Two of the witnesses leapt into the river after failing to get Mr Gibson's attention. The driver later told police he did not see the girl fall in. He said:
I turned the boat around and she went under.
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His car was about to get towed away. But he had other ideas.
41-year-old Latvian Arnis Zalkalns was last seen at home in Ealing on Wednesday, 3 September. He was reported missing two days later.
He fell 30 feet to the floor. But despite the drama, it appeared the show must go on.