Five years ago, a band of environmental activists ambushed a train carrying fuel to Drax, the largest coal-fired power station in Europe. They roped it to a bridge, unfurled some banners, and symbolically shovelled some coal on to the tracks. The protest was eye-catching, but caused no serious harm. It lasted 16 hours; the cleanup cost around £40,000. The following year, in Leeds, 29 of the protesters were convicted under the 1861 Malicious Damage Act, and sentenced to community service or given a conditional discharge. They held they were not acting criminally but trying to protect the environment. On Tuesday, the appeal court took only a couple of hours to quash all the convictions. The prosecution, just as they did in the trial of another 26 environmentalists involved in the Ratcliffe-on-Soar protest, had breached elementary principles of a fair trial. They had relied on evidence gathered by an undercover police officer, Mark Kennedy, and there had been "a complete and total failure" to disclose either that fact or the evidence to the defence.

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