It is his pace, among his other skills, that makes Plunkett a vital cog in England's ODI side. Getty

Liam Plunkett says he feels "a hundred times better" after a slight technical tweak helped him rediscover the pace of old to put in a match-winning performance against Essex Eagles and secure Surrey's first Royal London One-Day Cup victory of the season.

Figures of 4 for 50 suggest a welcome return to form after a tough start to life with his new county, having left Yorkshire for London at the end of 2018. But the most heartening aspect for Plunkett and England ahead of the World Cup was the sight of the 34-year-old bowling as quick as he has done this year. It is this pace, among his other skills, that has seen him as a vital cog in Eoin Morgan's ODI side over the last few years.

Last week Plunkett was named in England's 15-man preliminary squad for the home World Cup. But concerns over his drop in pace over the previous six months, coupled with exciting fast bowler Jofra Archer's presence in the wider squad of 17 for the Pakistan series gave the impression that a last-minute change ahead of the final May 23 deadline could be in the offing.

Morgan as skipper has talked previously about loyalty and the former Durham and Yorkshire man has certainly served him well. He has been England's most effective seamer in the middle-overs with 71 ODI wickets since the start of 2016 - only Adil Rashid (106) has more, though Plunkett does have a superior strike rate of 28.5 to the leg spinner's 29.4.

But the drop in Plunkett's speeds was certainly a point for consideration, especially at the top level. Indeed, this dip was proving to be a problem in domestic cricket.

On Championship debut, he registered figures of 1 for 85 from 18 overs against Essex. Even the switch to his favoured 50-over format did not serve him well, with nought for 67 from seven overs and 1 for 57 from six, against Gloucestershire and Sussex respectively - both matches ending in defeat for Surrey.

But on Tuesday, with Surrey desperate to keep their Royal London Cup hopes alive and with their key quick Tom Curran sidelined with a knee injury - he is expected to be fine for England's weekend training camp in Cardiff - Plunkett stepped up. His key interventions came in his final spell when he as able to remove the set batsmen Simon Harmer and Essex captain Ryan ten Doeschate in successive balls before removing Matt Quinn to seal victory with 7.1 overs to spare.

Such a change, while not overnight, has come in a matter of days after bowling coach Richard Johnson noticed something in Plunkett's approach to the crease. Together, with the help of experienced South African and fellow Surrey quick Morne Morkel, a solution was devised.

"I just noticed something, the way I was running in, the way I was attacking the crease," said Plunkett speaking after the match. "Just looking at some old footage and some technical stuff with Johno (bowling coach Richard Johnson), and speaking to Morne a little bit. Morne's only a year above me but he's played a lot of international cricket with some good cricketers. I looked at some footage with him and Johno and it wasn't much different.

"But it was like a tiny bit to the way I was running in. We're talking small margins where my foot was on the crease - we're talking inches. It wasn't like I'm trying to change my action. It's nothing to do with that, it's just the line of my run-up into the delivery."

The issue, said Plunkett, had him falling away slightly, forcing him to sling the ball down rather than his characteristically tall and straight approach that helps him generate his speeds. "I probably lost coming over the top of it (his action) a little bit and you're trying to force it to try and bowl quick. You actually lose your pace because everything is not behind it.

"For me, you want to intimidate you want to have a quick bouncer. You might not use it but people know you've got it. But you're bowling at 82 or 83 (mph) the bouncer can get slapped. It's nice to have that one to ping through to put people on the back foot. That's how you get your wickets."

Plunkett is unsure when this kink came into his game, but believes it has something to do with the amount of limited overs cricket he plays around the world on flat wickets which can force a bowler to lose his action by putting more effort in at the point of delivery. As it happens, the biggest red flag came with the red ball.

"Playing four-day cricket, you notice it more," said Plunkett. "If you're running in with a red ball and it's swinging, and you're slightly off it, you're going to bowl wides, you're not going to bowl accurate. Sometimes you can get away with that with the white ball, but your pace might be down because you can sort of muscle it down and it doesn't swing away so you push it there.

"Honestly, I'm glad I found that out because I feel like I can go back to bowling quicker with what I've found out the last week or so. I worked on it and felt so much better today. I felt I attacked the crease much better, my pace was in the late eighties and I felt like I had some 'snap' and some control.

"I felt a hundred times better. Even if I didn't take the four wickets, even if it was just one, I'd have felt like I've got something out of this game."

Though Plunkett does admit a few nerves might have contributed to his tough start to the summer - "if you're not getting the wickets you put pressure on yourself" - he certainly does not believe doubts over his place in the final 15 have clouded his mind. Nor is he put off by the looming shadow of Archer.

Chris Woakes, Mark Wood and David Willey have all had their say on the 24-year-old and the threat he poses to their respective World Cup spots. Plunkett, who is perhaps the most vulnerable, is pragmatic on the issue.

"Obviously he's been picked - he's a good bowler. But if it wasn't Archer, it would have been someone else. At the end of the day when you get picked you step out and try and do the same thing. That never really bothered me that whole situation.

"I feel like I was cranking up to where I want to me and I felt like the old me of the last few years."

Along with Curran's absence, England selectors will be closely monitoring Surrey's Jason Roy who suffered a back spasm in the match. The England opener retired hurt on 16 before returning at the end of the 46th over with Surrey 241 for 7. He finished unbeaten on 35, doubling over when striking his only six of the innings and did not take to the field.

There was also an injury to 2018 Test debutant Ollie Pope who damaged his left shoulder failing to stop a four on the point boundary.