An undercover cop has been exposed as one of the authors of a libelous anti-McDonald's leaflet that ended up resulting in the longest civil or criminal trial in English history.

In a new book called Undercover: The True Story of Britain's Secret Police, authors Rob Evans and Paul Lewis reveal that police officer Bob Lambert infiltrated the environmental group London Greenpeace and in 1986 helped around four other members pen a pamphlet that came to be known as the "McLibel leaflet." The publication, only a few hundred copies of which were ultimately distributed, put forth a thorough critique of the fast-food chain, saying its product were bad for the environment, people's health, and its own employees. The leaflet was "like his baby," a friend told the Guardian of Lambert's part in the matter, "he carried it around with him."

Lambert's undercover deployment ended in 1989, at which point he disappeared, "claiming that he had to flee abroad because he was being pursued" by his former employer, according to the Guardian. Lucky for Lambert, his vanishing meant he wasn't around when McDonald's sued two of the pamphlet's authors, Helen Steel and David Morris, for libel.

The trial, in which Steel and Morris defended themselves for lack of being able to afford an attorney, lasted 314 days, with McDonald's spending millions on attorneys. Steel and Morris eventually lost the trial, at which point they were ordered to pay £40,000 in damages. But the case didn't end there.

After losing to McDonald's, Steel and Morris went to the European Court of Human Rights to contest the fairness of their trial and English libel laws. In 2005, 19 years after helping to write the original leaflet, the duo won this new case:

The Strasbourg judges upheld their challenge today, saying the libel system broke their right to a fair trial under the European convention of human rights because they had been refused legal aid.

The verdict also said the system had breached their right to freedom of expression under the convention, to which Britain is a signatory.

Throughout the decades of drama around McLibel, Metropolitan police never thought it important to disclose that a police action had been involved with the leaflet's creation until now.

During his time undercover, Lambert also participated in sexual relationships with four women, one of whom he impregnated before disappearing. The woman and her child only discovered that Lambert was an undercover cop last year.

A spokesperson for the Metropolitan police said that he "recognizes the seriousness of the allegations of inappropriate behavior" on behalf of the department and that an internal investigation is underway.

[Image via AP]