Newcastle (3) 8
Try: M. Tait Pen: Miller
Harlequins (13) 19
Try: Smith Pens: Clegg (4) Con: Clegg
Rory Clegg kicked 14 points as Harlequins claimed their first win in this season's LV= Cup and inflicted a second defeat on Newcastle.
Ex-Falcons star fly-half Clegg knocked over the first of four penalties on two minutes to put the visitors in charge.
Sam Smith raced on to his own chip for Quins' only try but ex-Flacons star Clegg kept the penalties coming.
Against the run of play, replacement centre Michael Tait crossed late on for a consolation but it went unconverted.
Newcastle director of rugby Steve Bates:
"This has been a great chance for our young players to get out and learn about first-team rugby.
"They played better in the first half but we did better as it went on and scored a good try at the end."
Newcastle: Catterick, Williams, Bobo, Davey, Biggs, Miller, Charlton, Ovens, Walker, Ward, Swinson, Sorenson, Williamson, M. Wilson, Afu.
Replacements: Amesbury for Catterick (56), M. Tait for Davey (62), Shiels for Ovens (53), Vickers for Walker (70), Brooks for Ward (58), Welch for Williamson (53).
Not Used: Hudson, Young.
Harlequins: Chisholm, Drauniniu, Lowe, Luveniyali, Smith, Clegg, Dickson, Croall, Cairns, Lambert, Stevenson, Robson, York, McMillan, Guest.
Replacements: Lindsay-Haugue for Luveniyali (44), G. Williams for Dickson (65), Brooker for Croall (53), Marler for Cairns (53), Johnston for Lambert (53), Matthews for Robson (65), Wallace for McMillan (46).
Not Used: Mordt.
Ref: Greg Garner (RFU).