This was Hewson's first appearance in the trophy and his previous two one-day games for the county had produced only three runs. His 45 came off 81 balls and included three boundaries while Hancock's 60 took 128 balls.
Hancock's half-hour no joke for Northants
By Peter Deeley at Bristol
Half-an-hour's inspired bowling from Tim Hancock - he collected three wickets in 10 balls - was the turning point as Gloucestershire clinched a 20-run victory over Northamptonshire in the NatWest Trophy first round yesterday.
Gloucestershire, who made 266 for eight, dismissed Northants for 246 with just over two overs to spare, thereby earning themselves a plum home tie with Surrey.
Hancock, who had hit a half-century on the first day of this rain-hit match, crucially removed Northants captain Kevin Curran, caught at mid-off and next ball had Tony Penberthy caught behind. He made another big breakthrough when the in-form Mal Loye swung him high to fine leg where Courtney Walsh took the catch.
Curran and Loye had revived Northants' interest after the early dismissal of overnight pair Russell Warren and Rob Bailey.
Curran and Loye added 93 for the third wicket and, although the late-order battled gallanty, defeat virtually signals the end of Northants' hopes of winning anything this season.