With England staring defeat in the face on their first outing since September's Ashes win, the pair defended a paltry 158-run target by dismissing their opponents for 105 in their second innings on the third and final day.
Left-arm spinner Giles, who was sidelined by a stomach upset on Tuesday, bowled a superb line and length to take four for 39 and pacer Plunkett returned figures of four for 16.
The fightback will lift the tourists' morale ahead of their three-match Test series against Pakistan, which starts in Multan on November 12.
England had resumed the final day on a precarious 39 for six, only 84 runs ahead with four wickets intact. Opener Marcus Trescothick, who hit a lifesaving 124 not out in England's first innings score of 256 for nine, again top-scored with 38 to help England to 112 all out in their second innings.
Giles, who did not bowl in Patron's XI's first innings score of 211, removed dangerous opener Yasir Hameed (30) and Bazid Khan (0) off successive deliveries to trigger a collapse which saw the home team slumping from 50 for none to 88 for nine.
Plunkett, who is fighting for a Test place against rival pacer James Anderson, removed Asher Zaidi (26), Asim Kamal (0), Faisal Iqbal (2) and Misbahul Haq (14) in a spell of seven overs to open the doors for England.
From the other end, Giles kept up the pressure by sending Shahzad Malik (3) and Khalid Latif (0) to the pavilion, while veteran off-spinner Shaun Udal wrapped up the innings by claiming Yasir Arafat (4) and Zulqarnain (4).
Earlier Patron's XI seamer Yasir Arafat chipped in with five for 31 - nine for 76 in the match - to dismiss England half an hour before lunch.
Arafat had Ian Bell (1), Ashley Giles (0) and Matthew Hoggard (0) to nudge the memories of Pakistan's selectors, who have forgotten him since he played two one-day matches three years ago.
Trescothick added an invaluable 56 runs for the seventh wicket with Paul Collingwood who made 34.
England's top order flopped twice in the match with opener Andrew Strauss, captain Michael Vaughan, Ian Bell and Kevin Pietersen failing to get much needed practice.
They have another three-day side match, starting in Lahore from Sunday, to sharpen up their act before the Test series.
SCOREBOARD
ENGLAND (1ST INNINGS): 256-9 dec (M. Trescothick 124 not out, M. Prior 50; Yasir Arafat 4-45):
PCB PATRON'S XI (1ST INNINGS): 211 (Shahzad Malik 37; Udal 3-36, Plunkett 3-41, Anderson 3-50):
ENGLAND (2ND INNINGS - OVERNIGHT 39-6):
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A. Strauss c Bazid b Shah 6
M. Prior c Arafat b Irshad 16
A. Loudon c Zulqarnain b Irshad 1
M. Vaughan lbw b Irshad 0
K. Pietersen b Arafat 10
P. Collingwood b Shah 34
G. Jones b Arafat 0
I. Bell lbw b Arafat 1
M. Trescothick not out 38
A. Giles b Arafat 0
M. Hoggard c Zaidi b Arafat 0
Extras: (B-1, LB-4, W-1) 6
Total: (all out) 112
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Fall of wickets: 1-18, 2-19, 3-23, 4-38, 5-38, 6-38, 7-46, 8-102, 9-105
Bowling: Shah 11-1-34-2, Irshad 11-2-42-3, Arafat 12.1-4-31-5
Overs: 34.1
PCB Patron's XI (2nd innings):
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Asher Zaidi c Anderson b Plunkett 26
Yasir Hameed c Strauss b Giles 30
Bazid Khan lbw b Giles 0
Misbahul Haq c Trescothick b Plunkett 14
Asim Kamal c Trescothick b Plunkett 0
Faisal Iqbal c Prior b Plunkett 2
Shahzad Malik b Giles 3
Khalid Latif c Strauss b Giles 0
Yasir Arafat c Prior b Udal 4
Zulqarnain c Vaughan b Udal 4
Tahir Khan not out 8
Extras: (LB-9, W-5) 14
Total: (all out) 105
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Fall of wickets: 1-50, 2-50, 3-65, 4-65, 5-71, 6-75, 7-75, 8-87, 9-88
Bowling: Hoggard 9-3-16-0, Anderson 5-0-17-0, Giles 12-3-39-4, Plunkett 7-0-16-4, Udal 3.5-0-8-2
Overs: 36.5
Result: England won by 52 runs
Umpires: Riazuddin and Z.I. Pasha.