The tourists, who are set to begin their three-Test series against England at Lord's on Thursday, resumed at a lowly 68 for five in their second innings, still 12 runs away from making their opponents bat again.
But instead of some late resilience, Sri Lanka were bowled out for 118 Saturday and England A reached their victory target of 39 early in the second session.
Sri Lanka's Australian coach Tom Moody, who used to play and coach here with Worcestershire, might have at least expected his side to show some late order application.
Instead he saw Tillakaratne Dilshan set off in One-day style by smashing Surrey all-rounder Rikki Clarke for successive fours in the second over of the morning.
Dilshan, top-scorer with 47 during Sri Lanka's first innings, was the only batsman to offer significant resistance as the tourists lost their last five wickets for 38 runs.
England, who are due to name their Test squad today, are currently without injured pacemen Stephen Harmison, Simon Jones and James Anderson.
And England A seamers Liam Plunkett and Jon Lewis both bolstered their hopes of a call-up on Saturday.
Sri Lanka's morning slide began when Chamara Kapugedera attempting a cover drive off Durham's Plunkett, who is hopeful of being included in England's Test squad being announced on Sunday, was caught behind by wicket-keeper Chris Read.
Lewis, who took six wickets in the first innings, then tied down the Lankans with a six-over spell costing just four runs.
It was all too much for Farveez Maharoof who, trying to hit Lewis through the infield, found A team skipper Robert Key at mid-on to give the Gloucestershire seamer his ninth wicket.
But it was Stuart Broad, the son of former England opening batsman Chris, who took the keystone wicket of Dilshan for 42 as the England selectors, who were at the ground to meet to pick the Test squad, looked on from the boundary.
The Leicestershire teenager surprised Dilshan with a rising ball outside off-stump which the batsman could only edge to Alastair Cook at second slip.
Broad finished the innings by having last man Lasith Malinga also caught by Cook at slip, ending with impressive figures of three for 17 from 11.3 overs.
Chasing 39 to win, England A needed just eight overs to reach their target with Cook 22 not out and Key unbeaten on nine.