Six decades after Clint Eastwood nonchalantly used a cigar to light a cannon’s fuse in The Good, the Bad and the Ugly to fell a fleeing Eli Wallach, the Manchester-made weapon has been rediscovered in a museum in south-east Spain.

The artillery piece was tracked down by the Sad Hill Cultural Association, a group of volunteers dedicated to restoring the graveyard near Burgos, northern Spain, built for the climax of Sergio Leone’s seminal spaghetti western.

After coming across images of the cannon in a book on the film, the association set about trying to trace some of the weapons used in preparation for the 60th anniversary of the movie’s release later this year.

The 75mm cannon, made in Manchester by Whitworth in 1873, was one of the antique arms lent to Leone’s production team by the Spanish military. After filming it was returned to the army museum in Madrid. There it languished on outdoor display until 2010, when the museum and its collection were moved to Toledo.

A few months ago, Diego Montero, treasurer of the Sad Hill Cultural Association, visited the Toledo museum to look for the cannon. Further research led to the south-eastern Spanish city of Cartagena, where Montero discovered a group of retired soldiers had been restoring a 19th-century British cannon from the local military history museum.

“A few days ago we wanted to check the photos from the book against a more detailed photo, so we wrote to the director of the Cartagena museum, and he sent us a closeup photo of the top of the cannon and of the piece’s number,” said Montero. The serial numbers matched.

“The museum had no idea that they had the cannon that was used in the film. We told them that we were going to put out a press release because we knew that a lot of people would be interested – and they’d get loads of visits.”

The city council is certainly keen to use the cannon’s fame to draw more visitors. It posted on social media on Monday: “Did you know that one of cinema’s most famous cannons is in Cartagena and that you can visit it for free?”, with the post accompanied, inevitably, by Ennio Morricone’s genre-defining theme.

The museum’s director, Lt Col Ernesto Terry, said the cannon’s fame was already causing a stir.

“We had no idea this was the cannon from the film,” he said. “It’s been crazy and I’ve been talking about it non-stop to the media and to people who have been ringing to ask me about it. It’s been madness and we’ve had a lot more visitors.”

While the Sad Hill Cultural Association would love to borrow the cannon and temporarily reinstall it in the Burgos landscape, where it last stood 60 years ago, its protected heritage status means that will not be in time for the anniversary.

“The bureaucratic procedures are very lengthy, and we don’t have time,” said Montero. “But we’ll definitely try to do something in the future. Maybe we can get hold of the piece and at least bring it to Burgos, because there’s a military museum there.”