Hundreds of people will join a protest today aimed at persuading ministers to reverse a decision not to hold a public inquiry into violent clashes between striking miners and police officers at the Battle of Orgreave.
A year ago, Home Secretary Amber Rudd ruled out an inquiry into the events at Orgreave, Rotherham, in June 1984.
Scores of miners were arrested during a day of violence, and many were injured, although all charges were later dropped.
The Orgreave Truth and Justice Campaign will hold Halloween protest in Sheffield today, including a procession through the city, with a coffin leading the way.
Joe Rollin, the group's chairman, said plans were still being made for a legal challenge to the Government's refusal to hold an inquiry.
He said: "Theresa May's rhetoric about tackling burning injustices was clearly ignored by Amber Rudd.
"For this Conservative Government it is establishment business as usual. For many the wounds of Orgreave are as fresh as if it was yesterday."
Former miner Kevin Horne, one of those arrested at Orgreave, said: "Orgreave was a seismic event in our history. You have to wonder what the Government is so afraid of in revealing the truth.
"The outcome will be unpleasant but the continuation of deception and a flawed picture is an even uglier threat to the future of justice in Britain."
The clashes between thousands of police officers from across the country and pickets on June 18, 1984, became known as the Battle of Orgreave.
Violence flared at a British Steel coking plant at Orgreave as miners manned a picket line as part of a national strike over job losses and pit closures.
Campaigners fighting for a public inquiry into the incident blame the then government for being behind the police tactics on the day to break the morale of the National Union of Mineworkers, which organised the national strike.