Anticipation for rock shows by British artists soon reached fever pitch. As music venues grew bigger in order to meet the greater demand, the sheer volume of screaming fans presented a problem: the bands themselves were being drowned out in the midst of all the excitement. Large-scale audio distribution via high-tech PA systems was still a way off – and so the likes of The Who’s Pete Townshend suddenly needed louder amps to wage their assault from the stage. Jim Marshall was the man to supply them.

“Townshend wanted a cabinet containing eight 12-inch speakers,” Jim recalled in an interview with The Guardian newspaper in 2012. But even this newer, louder innovation wasn’t as straightforward as it sounded. The prototypes were so heavy that roadies struggled to get them in and out of the venues.

The gambit paid off, and the resulting JTM45/100 – a seven-foot-high monster of speaker power – became the first of what is now recognised as the definitive Marshall stack; the forerunner to the 100-watt Marshall of today. The introduction to this new revelation was held with The Who themselves at a pub in Southall. “We were all completely blown away,” recalled Marshall legend Jim Nairn – who, like everyone else present, had never heard a 100-watt amp before.

With the Marshall stack unleashed, the volume war was then truly underway. By the ‘70s, the stacks were being piled on top of each other, leading to titanic walls of sound that were as visible on stage as they were audible out front. The sound of that decade was all but confirmed by this groundbreaking creation, as the likes of Led Zeppelin and Black Sabbath each turned to Marshall thereafter. British bands have been making a noise in the States ever since.