For all the dynamite and bloodshed, some of the film’s most powerful moments are its quiet, reflective exchanges. When Mapache abducts one of them – a native Mexican named Angel (Jaime Sánchez) – the Bunch abandons him. But with nowhere else to go and nothing to do but redeem themselves, Bishop gives the command to rescue Angel. “Let’s go,” he tells the Bunch – a moment of skin-prickling manliness. As per the code, the Bunch now only have each other. Without each other they have nothing.

The Wild Bunch collect their weapons and walk to confront Mapache – an iconic shot. Peckinpah improvised “the walk” on the day – one of those moments that Cliff Coleman came to dread from Peckinpah. He was an obsessive perfectionist. Peckinpah made no bones about it. “A director has to deal with a whole world absolutely teeming with mediocrities,” he said.

The walk is magnificent and their battle against Mapache’s men, in the words of composer Jerry Fielding, is “a f—ing ballet”. The shooting begins when Mapache slits Angel’s throat in front of them. “The special effects department had rigged up a prop knife and a pump. The f—ing blood spurted from here to the f—ing street,” said Warren Oates. “It was just a malfunction of the pumping mechanism but it scared the s— out of everybody who saw the dailies. The producers were speechless.”

For that final shootout – “the Battle of Bloody Porch”, a “four against 400”-type situation – Peckinpah rigged the courtyard with 10,000 squibs, all controlled by a switchboard and timed to go off with the action.

Costume man Gordon Dawson had a production line going to repair the uniforms as they were torn to ribbons: “They’d come in bloody, ragged, torn, they’d be taped up, painted over the tape, stuck in front of a heater lamp to dry, a guy would go over the patch with dirty gloves to make it look like aged cloth, then they’d get blown up again.” He had just 350 Mexican soldier costumes; they were blown up 6,000 times.

Fifty years on, The Wild Bunch still strides ahead of the genre: like a slow, purposeful march towards a showdown between two old gunslingers that never happens. By the time Deke Thornton arrives on the scene, Pike Bishop is dead.

Thornton has his own moment of redemption – he rides off with the only surviving member of the Bunch, old-timer Sykes, to fight in the Revolution. “It ain’t like it used to be,” Sykes tells him. “But it’ll do.” It is, we can assume, Thornton’s own walk towards death. Peckinpah broke down when the film was finished. He spent a year with his editors, editing more than 300,000 metres of film.