Jos Buttler has admitted that Jason Roy, and maybe even Joe Root, could be added to the ODI squad to face Ireland next week, as England seek to give their senior players as many chances as possible to find form ahead of the World Cup, after a series win over New Zealand that posed almost as many questions as answers.

England’s 3-1 victory was notable for the displays of Dawid Malan at the top of the order, who was named Player of the Series for his haul of 277 runs at 92.33, while Ben Stokes confirmed that a year away from the format had done his World Cup readiness no harm with an astonishing 182 from 124 balls at the Kia Oval, England’s highest individual ODI score in history.

However, Roy was a notable absentee throughout the four games, after a series of back spasms prevented him from staking any claim for the opener’s berth that had appeared to be earmarked for him. And Root – another player who had not featured in ODI cricket since July 2022 – visibly struggled for rhythm throughout the series, making 6, 0 and 4 in the first three games, followed by a scratchy 29 from 40 at Lord’s in which he was twice dropped in single figures.

Harry Brook, the surprise omission from the original World Cup squad, failed to make a convincing case to oust Roy from the final 15, as he mustered 37 runs from 68 balls across his three appearances. And on the bowling front, too, there remains a degree of uncertainty around two other 2019 veterans, with Adil Rashid missing the final three matches of the series after picking up a calf niggle, and Mark Wood resting for all four games while managing a bruised heel sustained in the Ashes.

Speaking after England’s 100-run victory at Lord’s on Friday, Buttler reiterated the delicate dynamic that has driven England’s success in white-ball cricket since 2015. While he acknowledged that the current squad, with an average age of 32, has a “Dad’s Army” feel to it, he stressed that giving leeway to proven performers was non-negotiable if the team was to be freed up to play the expansive, no-fear cricket that has come to be its hallmark.

“We’ve tried to be a really loyal team and selection panel throughout,” Buttler said. “It’s something Eoin Morgan and Trevor Bayliss started. If you ask people to play in an aggressive way, then leave them out as soon as it goes wrong, it sends the wrong message. We’re asking people to take risks so there will be failures along the way. We’ve reaped the rewards of being consistent with selection so, certainly, you take whole picture in. You can’t just pick a World Cup squad from these four games.

“I wouldn’t call it ‘Dad’s Army’ but we’re an aging group,” he added. “We’ve got a lot of experience in the format, so it won’t take quite as long to get back to feeling completely at home in 50-over cricket.”

The upshot is that Buttler is keeping an open mind about the final squad shake-down, with England due to fly out to India on September 27, ahead of their opening warm-up game against the hosts in Guhawati three days later, and with their opening tournament fixture, against New Zealand in Ahmedabad, looming on October 5.

“Yes, obviously [the thinking about the squad] changes,” Buttler said. “We’ve played a series, so now you can let the dust settle on the series. Obviously, we’ve had a few injury niggles as well around a few players, so we can just gather a bit of information on that and then we can finalise the squad.”

England are planning to nail down any changes to their squad by Wednesday, the morning of the first of their three ODIs against Ireland, at Headingley. The second match follows at Trent Bridge on Saturday, but the third – a day-night fixture in Bristol on September 26 – is arguably too tight a turnaround for those players who are due to fly out to India the following day.

However, with the final ICC deadline coming up on September 28, there could still be time to make a late switch if Roy in particular is unable to make a convincing case, with either his form or his fitness, in those first two games.

“We just have to find out,” Buttler said. “The biggest frustration is for him. He wants to be fit, and playing, and affecting games of cricket for England. He’s been working really hard to be fit and available, but we now have a few days where we can regroup with the coach, the captain, the selectors, and just work out exactly what we need to do moving forward.

“In an ideal world, we’d have had a fully fit team to select from and give games to, but we haven’t been in that position, so that’s probably why we just need to take a day to work out exactly what we need to do before we do get on the plane to India.”

Whether that includes extra game-time for Root too, Buttler conceded that “everything’s an option”.

“With a guy as experienced as Joe Root, you can clearly just ask him ‘what do you need before a World Cup?’ and he’ll be able to give an answer as to what he’d like to do. It’s been an option all along to potentially add guys to the Ireland squad if needed, so we’ll get a clearer picture from everyone now that this series has finished, as to who needs what moving forward.”

Whatever changes England do make, however, Jofra Archer’s inclusion for the Ireland series is unlikely to be among them. He trained with the England squad at The Oval and Lord’s, as he continues to test his long-term elbow injury ahead of a potential role as a travelling reserve at the World Cup. However, Brydon Carse, a late addition to the ODI squad after impressing in the T20Is, could also be a World Cup contender after bowling with pace and accuracy in his one 50-over appearance at Lord’s

“There’s a huge duty of care to [Archer],” Buttler said. “He’s been out of the game for a while, and he’s still a young man who’s got a lot of cricket ahead of him. It’s obviously exciting to see him in an England tracksuit and bowling and, even when he looks like he’s going through the motions, he creates a lot of speed. So yeah, he’s a superstar. We’ll find out again more over time as to how he’s always travelling, but we’re excited that he’ll be back on the park soon.”

There are no such doubts about Malan and Stokes, however, the stand-out successes from the New Zealand series.

“He’s played fantastically well,” Buttler said of Malan, whose century at Lord’s enabled him to reach 1000 ODI runs in just 21 innings, equalling the England record set by Kevin Pietersen and Jonathan Trott. “Every time he’s had his opportunity, not just this series but before, he’s been incredibly consistent. After the second game we spoke about getting back to how we want to play our cricket, being more aggressive, taking more options, and the way he put the bowlers under pressure today was brilliant.”

And though Stokes did not play in the Lord’s ODI, Buttler knew he had seen more than enough during his Oval onslaught, a performance that confirmed the wisdom of his decision to reverse his 50-over retirement.

“It was an amazing innings the other day. You know what you’re getting when you bring Ben Stokes back into the squad. I’m delighted that he’s available for the World Cup. We obviously know what he can do on the pitch, but everything he brings to the team off it is great as well.

“I think also that it was great for his confidence, coming back after a year or so. Even a player, as great as he is, you probably want to just get your feet under the table again and have a good innings. And he’s gone and had the highest score in one-day history for us so yes, it’s a great place to be.”