The Test tsar watched on from a distance as a once-trailblazing outfit fell apart, culminating in two failed World Cup defences in the space of nine months. Matthew Mott lost his job as limited-overs coach as men's managing director Rob Key sought a change of leadership, and Buttler was lucky to stay on as captain.

Tactical errors across both 2023's 50-over World Cup and the T20 edition earlier this summer, combined with undulating form with the bat, wore heavy on Buttler's shoulders. As such, a once free-spirited cricketer, integral to England holding both ODI (2019) and T20 (2022) titles, adopted a far chippier disposition on the field and with the media.

While McCullum will only take the white-ball reins from the start of next year with Marcus Trescothick holding onto them until then, getting Buttler back to his old, relaxed self is top of his priorities. "He's been a little bit miserable at times," McCullum said of Buttler. "I think he's not naturally as expressive as what some may be.

"But I think he's done a great job, right? He won a [T20] World Cup as captain. He's been part of World Cup-winning teams previously as well. He's an incredibly gifted player. He's a fine leader.

"My job is to get the best out of him so that all those that sit in the dressing room feel like they can be 10 foot tall and bulletproof when they walk out to play. And they know that the skipper is going to give them that extra pat on the back and enjoy the ride with them. So it's a great challenge. I'm so excited about it, and I know that Jos is too, which is great."

"When I started the gig with the Test side, Stokesy and I knew each other - we had a natural respect for each other - but I wouldn't say we were mates," McCullum said. "What we've developed over the last couple of years is a very close friendship, to the point where I call him a very close mate. As much as you do this for cricketing reasons, ultimately you want good friendships and relationships to develop that last far longer than the time you've got in the job.

"Jos and I actually start from a stronger base. We know each other, we're mates, we have similar styles of play in our game. What I want from Jos is for him to enjoy the next few years. If he was to retire today, he'd go down as probably the greatest white-ball player England's ever produced.

"So, the opportunity for the next three or four years, however long he plays for, is just to enjoy it. Not to protect anything. Just get the most out of all those guys around him, keep walking towards the danger, play with a smile on his face and try to do something which is really cool. Where you can look back and say: 'Gee, I really enjoyed those last few years'. I'm sure our relationship will go from mates to very good mates."

As for that friendship with Stokes, McCullum hopes to use it to squeeze more appearances in coloured clothing out of his Test captain.

With Test captaincy Stokes' main priority, what itches he has for the white-ball cricket are scratched across the franchise circuit, which will include a maiden stint in the SA20 for MI Cape Town this winter. McCullum expects Stokes to stick around as captain throughout his tenure, which has been extended to 2027. As for his limited-overs future, there is a conversation to be had.

"The skipper and I haven't spoken about that [carrying on in Tests] actually, but I'm assuming he's all-in," McCullum said. "He seems like that sort of bloke. He's been incredible and our relationship is fantastic.

"You never know where the game's going globally and what sort of opportunities will pop up for him which will challenge him, but I know how invested he is in English cricket and how determined he is to drive this team forward. I'd assume that will involve him being in charge for that period of time - even though he's building a group of leaders around him that are growing and prospering in those leadership roles, too.

"In regards to the white-ball - yeah, why not? I guess we'll see where he sits. He loves big moments and big stages. As we'll have to do with all our players, there'll be times when they can't play everything, so there'll be some bilateral series where we simply can't have all of our best players playing at the same time. But when it comes to major events and big series, I think those players are very much in those discussions."