Last week's 3-0 T20 series clean sweep placed low expectations on these three ODIs but Sri Lanka are one spot above England in the 50-over world rankings and restricted their opponents to 265.
Five of England's top six got past 30 but only Harry Brook, with 67 off 69 balls, went to a half-century, one of the only batters to find fluency on a slow, low pitch.
A batting line-up famed for its powerhouse abilities was unable to hit a single six, albeit at one of the biggest grounds in the country, but Sri Lanka never came close to ending their barren run against their hosts as they were all out for 176.
Jacks followed up his 46 not out, which ensured England reached what seemed a competitive total at halfway, with an ODI-best five for 22 – outshining fellow spinner Rehan Ahmed, who took one for 46 after being drafted in for his injured mentor Adil Rashid.
England have now won their last 10 limited-overs meetings against Sri Lanka in 2026, while this was a fifth triumph in their last seven ODIs, an uptick after losing 11 of 15 50-over matches last year.
With next year's World Cup in southern Africa just over a year away, Brook may be encouraged that his side showed they could grind their way to victory rather than simply outmuscling their rivals.
Along the way Tom Banton's audition as the latest opening partner to Ben Duckett fell flat, the recalled right-hander making 10; Joe Root passed 23,000 international runs in making 44; and Duckett made 32.
Brook's dismissal, holing out to deep cover after charging Dushmantha Chameera, presaged a collapse from 3-182 to 7-211 as debutant legspinner Sachindu Colombage made a fine debut taking three for 44.
Jacks ensured England made a defendable, if not imposing total but it looked in reach as Sri Lanka made a solid start reaching 2-82.
But the following eight wickets added only 94. Captain Kusal Mendis, who missed the T20 series with injury, top scored and looked in good touch for his 42 before being dismissed lbw attempting to sweep Jacks,
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