The sun duly set on Sri Lanka's tour of England, but the literal setting on a sunkissed day in Hampshire proved infinitely more impressive than the figurative version. As a packed house at the Ageas Bowl revelled in another show of force from an increasingly impressive England white-ball team, the visitors prepared to exit stage left - trampled underfoot at the end of a long and arduous tour from which the positives will only be visible if their talented young players can learn from the experience and turn it to their country's advantage in the future.

For today, however, it was all about England's here and now. Liam Dawson pleased his Hampshire home fans by starring on debut with figures of 3 for 27 in four overs, before Jos Buttler - offered an unexpected opportunity to open the batting - eased England to a clean sweep of all three formats (and a resounding 20 points to four victory in the inaugural Super Series) with 73 not out from 49 balls, including three fours and four emphatic sixes.

Victory was duly sealed by eight wickets and with 15 balls left unused, thanks to an unbroken third-wicket stand of 114 in 79 deliveries between Buttler and Eoin Morgan, who rose above the dislocation of his left ring finger while taking a catch in the covers to produce his best innings of the year to date, an unbeaten 47 from 39 balls which included a firm swipe for six over wide long-on to cue the fireworks and wrap up England's first white-ball campaign of the summer.

Dawson, who was an unused member of England's World T20 squad, demonstrated his aptitude for the international stage by striking in each of his first three overs. In a composed and mature performance, he used his local knowledge to gauge the pace of the surface from the outset and cramp Sri Lanka's ambitions as they sought in vain to accelerate through the middle overs. On his watch, they collapsed from 58 for 1 to 82 for 5, including a crass first-ball run-out for Dasun Shanaka, their ambitions of a defendable total over there and then.

Dawson's fellow England debutant, Tymal Mills, was no less impressive even though his maiden international wicket will have to wait for another day. In two bursts of two overs, at the front- and back-end of the innings, he returned figures of none for 22, conceding a solitary boundary in each spell as Sri Lanka struggled to align his fierce pace with a cunningly disguised slower ball.

According to the speedgun, Mills' fastest ball was also his first - a 92.5mph loosener on a good length outside off stump, and that line rarely strayed at any stage of his performance, allowing Morgan to trust him implicitly at either end of the innings. It is early days in an England career that could have been over before it had begun when Mills was diagnosed with a degenerative back condition two years ago, but the early impressions were exciting in the extreme.

Then again, Sri Lanka's batting was as haphazard as you might expect from a side that has been through the wringer in all formats during their two-month tour of England. Despite Angelo Mathews' insistence, after winning the toss, that this contest was their opportunity to "end the tour on a high", many of the dismissals suggested that the only height that mattered any more was the cruising altitude of tomorrow's flight to Colombo.

"That has been the case for us right throughout the summer, we didn't get enough runs on the board," Mathews admitted afterwards. "We knew it would be a tough challenge but we just had to compete and give ourselves the best chance to win. Unfortunately either batting, bowling or fielding has let us down in every single game...140 was a very average score."

On a pitch that had been shown, by England's women during their hard-earned victory over Pakistan earlier in the afternoon, to be somewhat slower than might have been anticipated, Sri Lanka succumbed to a diet of half-formed mows and drives that they might have got away with, had the ball been coming onto the bat.

Instead, as Mathews conceded, it was "stopping and turning" a bit off the surface, and, as a consequence, their attempts at acceleration took on, at first, an air of desperation and then, latterly, resignation. Chris Jordan, in particular, took command at the death, returning from a minor mauling in the Powerplay to claim three wickets for six runs in his final two overs of the innings.

Liam Plunkett's heavy artillery accounted for the dangerous duo of Kusal Perera and Seekkuge Prasanna before either could fully cut loose, while Adil Rashid's wrist-spin was typically slippery and varied, and included a T20 collector's item - the first maiden of his 20-over career. Ramith Rambukwella, an offspinning allrounder whose only previous match had come against New Zealand at Pallekele three years ago, was tormented as he attempted to swing his way through the square boundaries. Though he eventually connected in Rashid's next over for one of only three sixes in the innings, he soon departed for 19 from 16 thanks to a direct hit at the non-striker's end from James Vince at point.

In reply, England's innings stuttered at the outset as Jason Roy - flushed with understandable confidence after his recent glut of ODI runs - stepped across his stumps in Mathews' first over to be bowled round his legs for a duck, before Vince made it 30 for 2 in the fifth over when he lost sight of a deflection off his pads and was stumped by Dinesh Chandimal as he strayed out of his crease in search of an non-existent bye.

By that stage, however, Sri Lanka believed they ought to have had the big one. On 5, Buttler appeared to graze a thin nick through to Chandimal behind the stumps but the umpire was unmoved. Snicko soon revealed a large spike as the ball passed the edge, but with no DRS on offer for the T20 leg of the tour, Sri Lanka had no recourse.

"Chandimal was pretty convinced he nicked it, but unfortunately it's one of those things, it happens," said Mathews afterwards. "T20 is a fast game and you want it to be fast. It was one of those days when you think you might need that one DRS. But it was human error once again and we couldn't do anything about it."

The same could broadly be said of England's run-chase, as Morgan appeared on schedule at No. 4, his finger numbed with painkillers and his timing and placement seemingly restored as a consequence. But it was Buttler's brilliance that ripped the game away. His promotion may only be a temporary measure, with Alex Hales rested for this game, but such was the clarity of his strokeplay and the inevitability with which he swept England to the spoils, you have to wonder if it may prove to be a longer-term plan.

"Certainly it's something we would consider again," said Morgan. "It's about getting the best of this fellow, because you don't know what his limits are - he's that good. His potential is as good as anyone's around the world. It's up to himself, me, TB [Trevor Bayliss] and Farby [Paul Farbrace] to be as open and honest about where his best position is to bat. But watching him crunch it is pretty awesome."

Where the white-ball game is concerned, however, such thoughts can be shelved until September. For now, England's attention turns back to Test cricket and the rapidly approaching Lord's Test against Pakistan. For Sri Lanka, a long flight home awaits. It's been a bruising visit.