Police were hammering the doors down when the riff to Deep Purple classic 'Smoke On The Water' was born.
The legendary rock band were jamming in a mobile unit after Switzerland's Montreux Casino burned down in 1971 during a concert by The Mothers of Invention after a fan had set the venue on fire with a flare gun.
And the cops came knocking the doors down because they were making a "hell of a racket".
Drummer Ian Paice recalled in an interview with Classic Rock magazine: "There was no sound-proofing and we were recording at night. A hell of a racket!"
Guitarist Ritchie Blackmore continued: "We did 'Smoke On The Water' there, and the riff I made up in the spur of the moment. I just threw it together with lan Paice. Roger Glover [Bassist] joined in. We went outside to the mobile unit and were listening back to one of the takes, and there was some hammering on the door. It was the local police, and they were trying to stop the whole thing because it was so loud. We knew that they were coming to close everything down. We said to Martin Birch, our engineer: 'Let's see if we have a take.' So they were outside hammering and taking out their guns ... It was getting pretty hostile."
Martin added: "It was about two in the morning, the neighbours were complaining.
"We locked all the doors. I mean, literally, it was 'da-da-da! Bang, bang', 'polizei, polizei' 'P*** off.'
"'Da-da-da'. So we had to get the track down before the police broke in and chucked us out."
The iconic riff could have easily got away amid the "hostile" situation, however, 'Smoke On The Water' ended up being the big hit from the band's 1972 album 'Machine Head'.
