The route looked simple on a map. From the harbour at Lyme Regis along the Jurassic Coast to the beach at Charmouth is about two miles, and on a kind day in summer it would be a beautiful paddle - red and grey cliffs on one side, gentle bay on the other. But March is not summer. The sea off Lyme Bay in late March averages around nine degrees Celsius, cold enough that someone immersed without good protection has perhaps a few hours before hypothermia takes hold. The wind that morning was from the north - blowing offshore, away from the safety of the beach. The instructors knew none of this with the precision it required. They had radios that did not work. They had no flares. They had not filed a route plan with the coastguard. Karen Gardner, Tony Mann, and the eight children were on the water without anyone ashore knowing where to look for them.

Dean Sayer's kayak capsized close enough to the shore that he could stand. He was helped up; the group regrouped; they pressed on. As the wind pushed them away from the cliffs and into open water, more kayaks capsized. The instructors tied the surviving boats together - rafted them - which can keep a group from drifting apart but cannot keep cold water from doing its work. The handyman waiting at Charmouth grew worried and raised the alarm only late in the afternoon. By then the group had been in the water for hours. When a Royal Navy helicopter finally found them, scattered across a wide stretch of Lyme Bay, the four children who died had been in the sea long beyond any margin of safety. The survivors remembered the cold and the waiting. One of the fathers later spoke of his daughter's anger that no one had come.

Months before the trip, a former employee of the St Albans Outdoor Centre had written to the managing director, Peter Kite, warning that the centre was running activities beyond its safe capacity. The letter ended with a sentence that would later be read in court: "You might find yourselves trying to explain why someone's son or daughter will not be coming home." Kite was convicted of manslaughter by gross negligence in December 1994 - the first time a director of a company had been convicted of corporate manslaughter in England - and sentenced to three years. The sentence was reduced on appeal and he was released after fourteen months. The centre had already closed; its lease was surrendered, its site eventually demolished in 2016 to make way for housing. There is now no building to point to. There are only four names.

Outdoor education in Britain had been self-regulating. After Lyme Bay, that stopped. David Jamieson, a Labour MP from Plymouth - the children's own city - introduced the Activity Centres (Young Persons' Safety) Bill, and it passed through Parliament in January 1995. The new law created the Adventure Activities Licensing Authority, working under the Health and Safety Executive, with the power to inspect, license, and shut down outdoor centres that took children climbing, kayaking, caving, or onto open water. It is a quiet kind of legacy: a body of inspectors, a clipboard, a checklist. But a generation of British schoolchildren has now grown up on residential trips and adventure weekends under that system, and in the thirty-plus years since the law passed, nothing on the scale of Lyme Bay has happened again. Dean, Claire, Simon and Rachel are why.