“We got a list of about 40 songs. Internally, certainly, I scoff - that’s almost three hours. This is insanity. What are we gonna cut?": Taylor Swift's bass player Amos Heller says he couldn't believe the length of the proposed setlist on the Eras Tour

With so much attention being focused on the sheer scale and spectacle of the thing, it was sometimes easy to forget that, working away in the engine room, Taylor Swift’s Eras Tour also featured an actual real-life band.

Thanks to a new six-part documentary on Disney+, though, we’re getting to learn a little more about the musicians who accompanied Swift on her record-breaking jaunt. The first two episodes of Taylor Swift: The end of an Era dropped on Friday (12 December), and in episode 1 we cut to bass guitar player Amos Heller in what initially appears to be a rather strange situation.

Heller is shown slapping his bass in a communal shower block in the bowels of one of the stadiums that Swift performed in. Strange behaviour, you might think, but he was there for a reason.

“I usually practice in the shower because I’m trying to respect the space and peace of everyone else,” he says, aware that his frenzied slapping might not be to everyone’s taste. “I go somewhere that people aren’t that much in,” he continues. “Showers are a good enough bet. I’m just trying to get some distance from everybody. It’s a lot.”

Heller has been playing with Swift since 2007, so has been able to witness her rise to superstardom first hand. “I think if I look back at it now, the thing that remains really constant is there’s not a challenge that she isn’t going to meet head on and kind of decide to conquer,” he says. “And having that kind of energy in the lead spot has inspired – I can say me personally – to do a lot of the same things.”

Despite being well aware of Swift’s work ethic and determination, though, Heller says he was still taken aback when he learned what she was proposing for the Eras Tour. “We got a list of about 40 songs,” he says. “Internally, certainly, I scoff - that’s almost three hours. This is insanity. What are we gonna cut? And I think we added three songs.”

In the end, of course, the tour was a triumph, but Heller admits that such a big swing could easily have missed the mark. “It seems obvious now, because it did work, but at the time, it’s a big risk to decide ‘we’re gonna do a three-hour-plus show, we’re gonna do it in stadiums, and we’re gonna do it all over the world,” he says.

Episode 1 of the documentary shows Swift in rehearsals not only with her band, but also Ed Sheeran, who came on stage during the ‘surprise songs’ section of the show at Wembley Stadium to duet with her on a medley that featured Everything Has Changed and End Game (both of which Sheeran co-wrote and featured on) and Thinking Out Loud. Backstage prior to the performance, we see Swift and Sheeran working out their vocal harmonies and reminding themselves of the chords for the songs as they strum on acoustic guitars.

The next two episodes of The End of an Era will be available from Friday on Disney+, with the final two arriving on 26 December.