Vitality Blast Finals Day, Edgbaston - Final
Somerset 124 (19.4 overs): Gregory 53; M Taylor 3-28, Payne 3-27
Gloucestershire 129-2 (14.5 overs): Hammond 58*, Bancroft 53
Gloucestershire win by eight wickets
Gloucestershire won their first T20 Blast title in glorious style as they comprehensively outplayed West Country rivals Somerset.
Openers Cameron Bancroft and Miles Hammond both hit half-centuries at Edgbaston as they won by eight wickets with 31 balls to spare.
Somerset's hopes of a trophy treble, which had been given such a big boost by Thursday's sensational County Championship win over Surrey, increased when they beat Surrey again in a well-contested semi-final.
But that treble dream ended when they proved to be simply no match for a Gloucestershire side who came from nowhere to squeeze through in the Southern Group, then followed it up with three straight Edgbaston wins.
The unlikely quarter-final victory over Birmingham Bears eight days ago, Saturday afternoon's eight-wicket win over Sussex and then this repeat eight-wicket walloping earned Gloucestershire their first knockout trophy win since 2015.
Somerset still have the Championship title and the One-Day Cup to go at, Gloucestershire became the 14th side to win the T20 - leaving Yorkshire, Durham, Derbyshire and Glamorgan as the only four sides who have not done so.
After being inserted by Gloucestershire, Tom Kohler-Cadmore got over his semi-final golden duck to make a bright start with Will Smeed, smashing 28 off the first three overs.
But Somerset then wobbled as Smeed steered Matt Taylor's first ball straight to backward point. And Taylor then added a second wicket in the over when he deceived Kohler-Cadmore with his slower ball and Tom Price took an off-side catch.
Taylor then had another off the final ball of his next over when James Rew was caught in the covers by a diving Cameron Bancroft. And, just two balls later, Somerset's other semi-final half-centurion hero Sean Dickson also fell cheaply first ball when he reverse-swept into his leg stump, off Ollie Price.
Tom Abell perished to Tom Price at long on, then David Payne struck twice in two balls when Benny Green was caught off a leading edge at backward point and Craig Overton looped a slower delivery to Jack Taylor diving forward to take the catch at mid off.
After Roelof van der Merwe was caught behind, captain Gregory eked a few more to go to his half-century before he was ninth out and Jake Ball was last out in the final over.
But 124 - the lowest first-innings score in a T20 final since Warwickshire made just 115 in the very first final in 2003 - never looked nearly enough.