After they were crushed in their opening games by co-hosts Australia and New Zealand, England posted 303 for eight after being asked to bat then dismissed Scotland for 184 from 47.2 overs on a day which began under dark clouds and concluded in bright sunshine.
Moeen Ali (128) produced a stream of delightful drives to reach his second one-day international century and shared a 172-run opening partnership with Ian Bell (54) to give England a grip on that match they were never to relinqish.
Although wickets fell regularly after their departures, captain Eoin Morgan at last found some form to strike 46 with four boundaries and two sixes and guide his team past the 300 mark.
Left-hander Ali was in prime form from the outset, driving the ball fluently through the off-side and punishing any short-pitched deliveries with some booming pulls.
He reached his century from 91 deliveries with his fourth six of the innings, lofting off-spinner Majid Haq high over mid-wicket.
Bell, who had been content to rotate the strike to give Ali the bowling, fell in the following over when he pushed a simple catch to Kyle Coetzer at cover from the bowling of Richie Berrington.
Ali pulled a fifth six into the crowd but then lofted Haq straight to Freddie Coleman at long-on.
After the interval, England's pace attack, which had been slaughtered by New Zealand captain Brendon McCullum in Wellington last Friday, took control.
Opener Kyle Coetzer took two boundaries off James Anderson's opening over and continued to drive and cut confidently to reach his half-century off 64 balls.
Runs dried up at the other end against disciplined bowling and his dismissal for 71 with 11 boundaries was the beginning of the end.
Ali took two for 47 from 10 overs, bowling in tandem with another occasional off-spinner Joe Root, as the wickets fell and the required run rate rose.
Finn, who was smashed for 49 from two overs in the humiliating loss to New Zealand last Friday, returned to help clean up the tail. He finished with three for 26 from nine overs.
