McCullum's unveiling in the role has been a long time coming. His new deal, as England's dual red- and white-ball head coach, was announced back in September, and he has since overseen consecutive Test tours of Pakistan and New Zealand while Marcus Trescothick covered the one-day role in an interim capacity.

Now, however, McCullum is straight into the hot seat, with a five-match T20I campaign against the newly-crowned T20 World Cup champions, followed by three ODIs against the finalists of the last 50-over World Cup in 2023, ahead of their Champions Trophy opener against Australia in Lahore on February 22.

Speaking at Eden Gardens ahead of the first T20I, McCullum described England's batting as being "as powerful as anyone's in the world", but said that, at this stage, he was more focused on freeing up his players to perform at their best, rather than gunning for outright victory.

"Obviously, we want to win every game we play, to try and be successful, and that's ultimately the mission for us," he said. "But our conversations and the language which we use within the dressing-rooms is quite different.

"It's about trying to get the best out of the talent that sits within the dressing room, trying to gel the guys as best we can, trying to work out complementary skills, and how we how we play the style of cricket that gives us our greatest chance.

"I'm desperate for us to play a really watchable brand of cricket," he added. "With the talent we have, there's no reason why we can't. We've got a batting line-up which is as powerful as any batting line-up in the world. We've got gun spinners, very good fielders and guys who bowl absolute rockets with the ball, so you've got options there to be able to entertain and give yourself the greatest chance of success."

McCullum takes over a white-ball set-up deep in the throes of transition, with the team having lost both its 50- and 20-over World Cup titles in the space of seven dispiriting months in 2023-24. His selections for this campaign, however, made it clear that he intends to use his joint coaching role to unify the Test and one-day set-ups, with eight of his 15 selections for the ODI squad having featured in the longer format in the course of 2024.

"He's smiling, that's good. He's very happy at the moment," McCullum confirmed, adding that his pre-existing relationship with Buttler, forged during his own playing days at the IPL and around the world, had enabled them to hit the ground running as a captain-coach combination.

"Obviously we've known for a couple of months that this was going to unfold, so there's been plenty of time to chat to Jos over the last couple of months," McCullum said. "When I took over the Test job, Stokesy and I knew each other and there was a mutual respect, but wouldn't say we were friends necessarily, even though it's now a really tight personal relationship, as well as a working relationship.

"With Jos, we actually start from a slightly stronger base. Jos and I have been friends for a long time, we've often shared some of the philosophies of game, and that friendship gives us really good base to be able to be able to get things going pretty quickly with this team.

"He's in really good space. He's excited about the team, and the opportunity that sits in front of us, I'm sure we'll see Jos really enjoy himself over the next couple of years, and hopefully finish with a real strong enjoyment for the game at the back end of his career."

McCullum also confirmed that Buttler would once again be relinquishing the gloves, in order to lead the team from the field rather than behind the stumps, with Phil Salt likely to continue in the role he took on for both series in the Caribbean in November.

"It's really a really positive thing for us, because it gives Jos the opportunity to have the last say with the bowler, and to have that relationship built at that last second, rather than from 22 yards away," McCullum said. "We've got great keeping options within the side as well."

At the age of 34, and as a double World Cup-winner, Buttler has little left to prove as one of the modern greats of the white-ball game. But, having witnessed the success and enjoyment that Stokes has got from leading the Test team over the past couple of years, McCullum believes there's scope for Buttler to put a cap on his own career in a similar manner.

"I think his best years are definitely ahead," he said. "Sometimes, when you get the opportunity to lead in the latter part of your career, you can be a little bit desperate for success and that can create frustrations, and it doesn't become quite as enjoyable.

"But if you can let yourself go a little bit, with nothing to prove other than trying to get the best out those around you, sometimes that can lift your game up a bit more. Those are the conversations Jos and I have had. He's fully on board with that, he's excited about the next little while, and I'm sure you'll see him smiling.

"It's going to be a tough tour. We're taking on a very good India side, and I'm sure we'll play what I hope is a very watchable style of cricket. I'm sure there'll be some times we don't quite get it right but, hopefully, we'll chisel away at that over the next few weeks and be in good shape come the Champions Trophy.

"But we are very much focused on this series, knowing India are a very good cricket team, particularly in their own conditions."