Andrew Strauss' team began by springing a surprise, promoting Kevin Pietersen to open the batting - and ended it with much more than they bargained for as Rizwan Cheema's thrilling counter-attack put Canada on the brink of a notable chase.
It seemed Canada had no chance in reply to 243 all out, after Stuart Broad (five for 39) and Ajmal Shahzad reduced them to 28 for five.
But Cheema (93) had other ideas, making a mockery of everyone else's laboured batting with a display of sustained hitting which contained 10 fours and five sixes from 70 balls to put his team well ahead of the run rate.
In the end, a victory margin of 16 runs grossly flattered England. They had earlier been indebted to Matt Prior (78), down at number six after opening the batting in five of this winter's seven one-day internationals against Australia, for his combined effort with Jonathan Trott (57) to muster a competitive total.
Pietersen has long been inked in at number four. But England revealed they intend to use him at the top of the order in this tournament, in preference to wicketkeeper-batsman Prior.
The new incumbent made an acceptable start, after the early loss of Strauss, until he became the second of three victims for Khurram Chohan.
Strauss chose to bat first but fell in the second over, under-edging a pull behind off the skiddy Chohan.
Pietersen was joined by Trott, only to go for 24 to Chohan - switched to the Pavilion End - when his attempt to squeeze a single off the medium-pacer resulted instead in an inside edge on to the base of leg stump on a predictably slow surface.
Ian Bell was unable to prosper either, trying to steer runs behind square on the off side but edging Chohan (three for 34) behind.
Paul Collingwood failed the patience test, stumped on the charge after missing a leg-break from Balaji Rao.
But the in-form Trott was ideally suited to awkward circumstances and responded with a typically hard-working 50.
Prior played admirably too - adding 54 for the fifth wicket with Trott, who went to a mistimed sweep at off-spinner John Davison - and then 51 with Broad, after Mike Yardy and Luke Wright both fell cheaply to Henry Osinde to put England back in trouble on 158 for seven.
Prior had to rein in his attacking instincts, and was counting only his third four when he pulled Osinde to the boundary to bring up a 60-ball half-century.
He was eventually bowled by a slower ball from Harvir Baidwan (three for 50) but helped to add an important 63 with the tail in the last 10 overs.
England were denied permission by the International Cricket Council to select stand-by fast bowler Chris Tremlett as James Anderson sat out the match with a stiff back - the Lancastrian is expected to be available against Pakistan on Friday.
But with the new ball, Broad proved his well-being after this week's stomach upset - working up good pace to intimidate Canada's top order, in his first match since suffering the abdominal muscle tear which ended his Ashes in Adelaide in early December.
Shahzad, back from a hamstring injury, helped Broad put Canada in instant disarray as both openers were bowled.
Davison played all round a length ball from Shahzad, and Nitish Kumar edged Broad down on to off stump.
Broad soon added the wicket of Ashish Bagai, the Canada captain backing away to try to carve off-side runs and looking astonished when he merely presented Pietersen with a routine catch in the gully.
The procession continued as Jimmy Hansra aimed across Shahzad's full-length swing and was lbw in front of off stump, and Broad had three when Ruvindu Gunasekera flailed an edge behind.
Cheema, choosing an entertaining method which went well beyond mere damage limitation, more than trebled the score with Zubin Surkari for the sixth wicket.
Surkari was well caught by Collingwood away to his left at cover, driving at Yardy.
But Cheema, having found a new ally in Chohan, escaped a half-chance on 68 to a tumbling Yardy off Collingwood at short third-man - and greeted the return of Broad with two huge leg-side sixes.
Another attempted big hit at Broad saw him caught at last at long-off to end a stand of 60 in only nine overs.
Yet still England's superiority was in serious doubt, as Chohan shepherded the tail - until he was last out, lbw to the returning Broad with almost four overs still remaining.