Stuart Broad hailed the mentality new Test coach Brendon McCullum has instilled in England, with the New Zealand great encouraging his side to play with freedom.

England completed a fourth-innings chase of 279 in the opening Test against the Black Caps at Lord's, with Joe Root posting a majestic unbeaten 115 to guide his team to victory.

But more fireworks were to follow at Trent Bridge when England chased down 299 in just 50 overs on the final day as the McCullum era got off to a magnificent start.

Jonny Bairstow bludgeoned the second-fastest Test century for England on Tuesday, with new captain Ben Stokes providing more than capable support to take an unassailable 2-0 series lead over New Zealand in the three-match series.

Much has been made of McCullum's coaching methods, which are said to focus on mentality as opposed to technique during the match, and Broad was quick to credit his coach.

"There's no doubt that Baz has had an impact already," said Broad.

"It does feel really fresh and exciting in the changing room. It's a very positive language. It's very forward-thinking, all about how to move this game forward.

"This is no dig but at tea, when we were four down with the game in the balance slightly, I've certainly been in changing rooms in the past where that would be shut up shop time.

"Baz's team talk was very much 'let's attack the danger; let's run towards the danger' so every part of your mind is about going for this win.

"It was never really a case of 'if we lose one we might shut up shop'. It was always 'we're going to win' and if it doesn't work, don't worry about it."

Root has continued his batting form in impressive fashion after stepping down as England Test captain in April, with Stokes taking the role.

Chris Silverwood was also dismissed as coach and Broad says McCullum has brought the focus back to the excitement of cricket, with players enjoying the challenge and the occasion.

"I don't think he's spoken particularly deeply, his whole mantra is about enjoyment and fun," he added. "The energy is: how good's Test cricket? How good's this ground? What can we get out of today?

"He looks like a guy who has a cricket brain that is working all the time, he's thinking how we can change the game.

"It's not just praising guys who get a hundred, it's tiny little things, bits of fielding, momentum changes in the game. He will bring attention to that."

While McCullum has enjoyed a great beginning to his role, downing the world Test champions in both matches, even the New Zealand legend may have not expected the heroics of Bairstow.

The Yorkshire star smashed a 77-ball century in a game-changing 179-run partnership with Stokes as England chased the remaining 160 runs in the final session with ease.

"I didn't quite expect to see what I saw from Jonny. It was the most outrageous hour I've seen in Test cricket from a partnership. It was just exhilarating, astonishing," Broad continued.

"That striking...only a handful of players in the world can do that. Jonny is obviously in that group."