The miners' strike 40 years on: The day relations between the police and miners changed forever

Giant wind turbines tower above the university campus in the distance, framed by the glass and steel frontages of the neighbouring technology companies.

And then, jarring incongruously with the scene of serene modernity, is a scruffy-looking footbridge covered in graffiti: "Scargill No.1" it says in one place. "Tories out!" in another.

This is where the Battle of Orgreave took place. The disorder, which saw mounted police clash with hundreds of pickets, looked more akin to a skirmish during the Norman Conquest than a modern-day industrial dispute.

At least 123 people were injured, although the NUM claim the figure was higher.

Journalist Alastair Stewart described the disorder as 'a defining and ghastly moment' that 'changed, forever, the conduct of industrial relations and how this country functions as an economy and as a democracy'. Historian and former Labour MP Tristram Hunt described it as 'almost medieval in its choreography... at various stages a siege, a battle, a chase, a rout and, finally, a brutal example of legalised state violence'. The left-leaning barrister Michael Mansfield said it was 'the worst example of a mass frame-up in this country this century'.

For Scargill, this was meant to be a re-enactment of Saltley Gate. His shutdown of the Birmingham gasworks had forced Ted Heath's government into total capitulation, and turned him into the most prominent trade union leader in the country. Now, he saw the same to do the same with Margaret Thatcher.

Scargill regarded the coking works at the former Orgreave Colliery, just outside Rotherham, as of crucial strategic importance in his battle with the Government. The plant turned coal into coke for use in steel production, and in the early months of the strike, the NUM agreed to limited movement of coal to prevent damage to steel furnaces. However, Scargill and many senior figures in the NUM became convinced that the National Coal Board was abusing this agreement, and exceeding its quotas.

An informal pact, known as the Triple Alliance, had existed between the NUM and the unions in the steel and rail industries, and Scargill asked steelworkers not to handle deliveries of coal. But Bill Sirs, leader of the Iron and Steel Trades Confederation (ISTC) defied Scargill's call, saying that it would put rolling mills and billet forges out of action, putting his members at risk of job losses. Sirs instructed his members to handle any fuel they were presented with.

Scargill's policy of targeting the steel industry was also met with some opposition within his own ranks. The steel industry was a major customer of the National Coal Board, and Scargill's deputy Mick McGahey was concerned that shutting down parts of the steel industry would simply lead to a decline in demand for coal. McGahey, was particularly concerned about the Ravenscraig steelworks in Scotland, which he had campaigned to save – he knew that just a single day's stoppage could sound the death knell for Ravenscraig.

Tensions were running high in Yorkshire following the death of Joe Green, a picket who was fatally struck by a trailer while trying to stop deliveries to Ferrybridge power station. Two days after Green's death, Scargill addressed a packed rally at nearby Wakefield where he made an impassioned plea to close Orgreave.

The following day, Scargill deployed 5,000 pickets from across the UK with the aim of closing the plant down. Determined there would be no repeat of Saltley Gate, South Yorkshire Police drafted in 6,000 officers from 18 different forces, and they were issued with full riot gear for the first time in the 12-week-old dispute. Among them were 42 mounted officers, and dog units were also called in. The battle lines were drawn.

On the morning of June 18, 1984, pickets began to gather at about 8 o'clock in an effort to stop the convoy of British Steel coke lorries from entering the depot. Hundreds of officers lined the road to ensure their safe passage, and a nervous stand-off took place.

According to Tristram Hunt, 'a few missiles and bricks were thrown', and assistant chief constable Tony Clement, the commander on the ground, responded by sending in the mounted police.

"It was a serious over-reaction and the miners' mood quickly turned violent," says Hunt.