"'Fancy doing another Trent Bridge?' was the first thing that we said," Bairstow told Sky Sports. "That was it: 'OK, let's crack on'. Sometimes it's a simple game that we complicate. That's all we're trying to do: strip that complicated nature of it back, allow people to go out and express themselves in a way that will bring the best out of them as individuals and also as personalities.
"There is sometimes a lot of rubbish spoken about a lot of different things. Sometimes it gets into your mind and clutters it; sometimes you have to just flick it. You have to listen to the people that matter to you and right now I am doing that.
"Literally, there wasn't anything said," Bairstow said, "just 'good luck and enjoy'." Asked if the simplicity felt new to him, he replied: "Or is that the way that people are so used to it happening? I don't know. I'm asking you the question. Is that the way that we're so used to it happening? Or is it just 'we trust you guys to go and play the way in which you see fit'?"
He described the change in attitude under McCullum and Stokes as "massive", adding: "It's a buy-in from everyone, from the head coach right down to the guys making their debuts and coming into the squad. Whether you've played 170 Tests like Jimmy [Anderson] or making your debut like Jamie Overton, everybody's buying into a certain way that we believe we're capable of doing - but also a way of Test cricket that is different to potentially the norm.
"It's a case of putting pressure back on other people. If you sit there, sit there, sit there, there's a good ball in there for you. Rather than being a sitting duck and saying 'look, alright, you can bowl at me' it's 'OK, you can't bowl at me, so let's go'."
Bairstow hit the sixth and seventh balls he faced for boundaries, both off Boult, and said that he had felt as though he needed to "transfer the momentum" after England's disastrous start. He continued to attack even after Stokes had chipped Neil Wagner to mid-off for 18 off 13 balls and Foakes had been trapped lbw, leaving England six wickets down early, adding an unbroken 209 with Overton in 37.1 overs to cut the deficit to 65 runs overnight.
"There's different ways of looking at it," Bairstow said. "You can either go into your shell and bat the way people have done for years and years and years - try to survive against bowlers like Trent Boult and Tim Southee when they're bowling so well. But you need to transfer the momentum, take them off their lengths. They were hitting their straps, conditions were in their favour.
"We're only a few games into it but we're definitely looking at it in a different way, going out and expressing ourselves, taking the game forward and hopefully playing in ways that can change games. You need people to stand up and change games. That's how you win games of cricket, whether it's a bowler taking five, six or seven-for or batters scoring hundreds."
Bairstow's hundred was his second at his home ground, and his first since 2016. "You know how much this place means to me," he said. "Being a Yorkshire lad scoring a Test hundred at home, it's pretty special. All my family and my mates are here.
"Every time you score a Test hundred it's emotional. It means so much to me to play Test cricket for England and that's the kind of guy I am: I wear my heart on my sleeve. Sometimes it's not everyone's cup of tea but I love representing this team, and I am really excited about the journey we are embarking on."
Matt Roller is an assistant editor at ESPNcricinfo. @mroller98