Liam Dawson has been called into England's World Cup squad at the expense of Joe Denly, while David Willey is the unlucky seamer to make way for the inclusion of Jofra Archer, as England's selectors unveiled their final 15-man line-up ahead of the tournament's opening fixture, against South Africa at The Oval on May 30.

James Vince has also been named in the 15 as a straight swap for Alex Hales, who was deselected earlier this month after failing two tests for recreational drugs, making a total of three changes from the provisional 15 that was named ahead of ODIs against Ireland and Pakistan this month.

"It was a very difficult decision," said Ed Smith, the national selector, at the squad announcement at Lord's. "David Willey was very unfortunate in missing out, he could easily have been in this World Cup squad, but that's sport. Sometimes there are more deserving people than there are places in the squad."

Dawson's inclusion completes a remarkable return to prominence for a player who has not been in the England frame since the ODI tour of Sri Lanka prior to Christmas. A side strain suffered on that trip opened the door for Denly, who marked his first England appearance for almost ten years with a four-wicket haul in a one-off T20I in Colombo.

However, having been earmarked as England's spin-bowling reserve allrounder for the World Cup, Denly failed to cement his place during the Ireland and Pakistan series. He bowled just 11 overs in three matches - in which his solitary wicket came from a leg-side stumping - while his innings of 17 from 21 balls in England's three-wicket win at Trent Bridge last week was not enough to convince the selectors that he has the batting prowess to be worth a place.

Smith added that Denly's focus would now be on playing four-day cricket for Kent, with a view to cementing his Test place ahead of this summer's Ashes.

"He's very clear in his situation, there were two things that could have happened," said Smith. "One, he would have been the World Cup squad. The other one is he goes back to Kent, has a good block of four-day matches before the challenges in the second half of the summer. So he was very clear that both avenues were possible to him."

Dawson, meanwhile, has been in impressive form for Hampshire in this season's Royal London Cup. He has claimed 18 wickets at 20.33 en route to the final against Somerset at Lord's this week, and he has also made 274 runs at 45.66, including a century against Surrey at The Oval. He is understood to have been withdrawn from Hampshire's ongoing County Championship fixture against Nottinghamshire on the Isle of Wight, with Mason Crane deputising for him.

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Dawson's inclusion in England's plans had been telegraphed earlier in the month, when the coach Trevor Bayliss hinted that he might be called up to the squad for the latter stages of the Pakistan series. Though that didn't come to pass, it was clear that he and England's captain, Eoin Morgan, were at odds with the chief selector, Ed Smith, a strong advocate of Denly's credentials, and Smith himself admitted that the final decision had been a "consensus" call rather than unanimous.

Bayliss ultimately conceded that the casting vote in the event of a selection disagreement would come down to the captain, Morgan, who had dropped a strong hint as to Denly's lack of suitability for the back-up spin role by bowling him for a solitary over - containing three full-tosses - in the third ODI at Bristol.

Smith described the role of the reserve spinner as a "very subtle balance issue".

"Do you tend towards someone who's mainly a batter who also is a very handy bowler in Joe Denly," he said, "or do you tend towards someone who's tilted more towards the bowling side of it but is also a handy batter? It could have gone either way.

"I would say that everyone in the room was comfortable with the squad that the selection panel has come up with," Smith added. "And I think it was very important for me as a selector, that the captain feels comfortable with the squad he takes into the World Cup. Eoin has been captain for over four years, the England one day side has done extremely well, this is the culmination of a long campaign, a lot of planning, the culture of that team has been very strong under Eoin Morgan. He's very comfortable with the squad, as we all are."

Archer, meanwhile, has completed a stunning rise through England's ranks, having only received the opportunity to qualify for the World Cup when the ECB changed its residency rules from seven years to three late last year.

Having made his name on the T20 franchise circuit, Archer showcased his value to England as a 90mph new-ball bowler in a sharp four-over spell in the rain-ruined first ODI against Pakistan at The Oval, then combined well with Mark Wood on a batsman-friendly surface at Trent Bridge the following week.

"We've seen Jofra Archer playing for England over the last few weeks, and we've seen the skills and the quality he has," said Smith. "It's pretty straightforward isn't it? He's a very good cricketer, very talented, a very exciting player. He has pace, bounce, athleticism, skill with the bat, he's an outstanding talent, that was clear to all of us. He's made a very good start to his England career and long may that continue."

His inclusion is cruel luck on Willey, who had been outspoken about the threat posed to his place when Archer first became eligible earlier this year. Nevertheless, he seemed to have risen to the challenge posed to his place in the squad with an impressive showing in the second ODI at the Ageas Bowl, where he showcased his death-bowling credentials to close out a tight 12-run win.

However, Willey was less impressive at other moments of the series - not least in being taken for 86 runs in ten overs at Bristol - and appears to have suffered, ultimately, from the lack of fallibility from his rivals for selection. Tom Curran impressed with bat and ball at various stages over the last two weeks, while Chris Woakes reaffirmed his status with a decisive five-wicket haul at Headingley.

Liam Plunkett, meanwhile, remains England's most prolific seamer since the 2015 World Cup, and the selectors are loath to go into the upcoming tournament without his experience. And Mark Wood, despite his injury concerns, was touching 90mph in what is so far his only spell of the summer alongside Archer at Trent Bridge.

Bayliss, who will stand down at England coach after the Ashes later this summer, said: "I hadn't seen [Archer] play live before but he's certainly lived up to expectations. He's got good control, good pace and he can bowl in all the three phases of the match.

"It's been a hectic last six months but the guys have come through and I fully expect them to play well," he added. "For any team, knockout cricket is when the most pressure is. Our first job is to get through and qualify for the semi-finals. Get to a semi and anything is possible."