More than 5,000 striking miners clashed with a similar number of riot police who had been drafted in from across the country at the Orgreave coking plant near Sheffield in northern England.

It was one of the most violent scenes witnessed during a British industrial dispute and also a pivotal moment in the strike, launched against Thatcher’s moves to close money-losing pits. The miners ultimately lost the broader fight to save their industry.

The police have long faced accusations of brutality and using excessive violence at Orgreave on June 18, 1984. TV footage showed charges by officers on horseback and one miner being repeatedly struck on the head with a baton.

More than 120 people were injured, and 95 miners were initially arrested and charged with riot and violent disorder. Those charges were all later dropped after the evidence was dismissed.

Campaigners have for years demanded to know who was responsible for the deployment of the large number of police and their tactics, as well as what happened to some official documents.

Home secretary Yvette Cooper – Britain’s interior minister whose Labour Party was in opposition at the time of the strike – said an inquiry headed by Pete Wilcox, the Bishop of Sheffield, would be held to find out the truth.

“The violent scenes and subsequent prosecutions raised concerns that have been left unanswered for decades, and we must now establish what happened,” she said.

Kate Flannery, the Orgreave Truth & Justice Campaign secretary, said they needed to be sure that the inquiry had the powers to have unrestricted access to all government and police papers.

“We have waited a long time for this day and this is really positive news,” she said.