Hampshire 190 for 6 (Prest 64, McDermott 31) beat Somerset 153 (Lammonby 34, Ellis 3-30) by 37 runs

Hampshire are one win away from equalling Leicestershire's record for the most English domestic T20 titles after a clinical 37-run win against Somerset set up a final against Lancashire at Edgbaston.

Last year, Somerset snatched an improbable victory against Hampshire in the day's first semi-final, recovering from 34 for 5 to chase down a target of 151 with two wickets and two balls remaining. This time, Hampshire were ruthless, posting 190 after winning the toss and taking regular wickets to defend that score comfortably.

Hampshire lost their first four games of the Blast this season but have now won 11 of their last 12. "It's 10 years since we won our last semi-final," James Vince said. "After 10 overs we set out to get 200 but the wicket lost a bit of its pace. The guys have been outstanding with the ball defending targets all year and that's exactly what we've done. That was the way we wanted to go. It's set up for a good final."

A young talent announcing themselves on county cricket's biggest stage has become an annual feature of Finals Day. This year, it was Tom Prest's turn. Prest, a 19-year-old top-order batter from Dorset, made the highest score of his fledgling T20 career to hold Hampshire's innings together and propel them to a match-winning total. He was the youngest half-centurion in Finals Day history.

"It's amazing to get that win after last year's disappointment," he said. "It's just been about playing with that freedom. We started firing at the right time and once you get on a roll in T20, it's hard to stop. It's what dreams are made of: I've always wanted to play in a final."

Prest captained England to the final of the Under-19 World Cup earlier this year and has been backed throughout this season despite a relatively lean return from No. 3. He made a triple-hundred in the Second XI Championship last season but most of his first-team opportunities have come in T20, where he looks to accumulate early on before cashing in.

He had the chance to take his time in this semi-final thanks to a bright start from Vince and Ben McDermott, the most destructive opening partnership in the Blast this season, who put on 47 for the first wicket in 4.2 overs, flogging Jack Brooks and Peter Siddle. Both were caught at extra cover looking to loft over the infield, but from 69 for 2 at the end of the powerplay, Hampshire were able to consolidate.

Prest was 30 off 27 balls when he was hit on the helmet looking to scoop Brooks and Hampshire's innings looked in danger of petering out, but reached his half-century nine balls later. He was strong off his pads, whipping Lewis Gregory for consecutive boundaries through square leg, and by the time he holed out to long-on in the final over, Hampshire had ensured they had a total they could defend.

Somerset were missing two of their best T20 bowlers in Craig Overton, with England ahead of Sunday's deciding ODI against India, and Josh Davey, who injured his hamstring in last weekend's quarter-final against Derbyshire. Perhaps they could have coped without one, but their attack looked toothless without both.

Will Smeed and Tom Banton both started brightly but the depth and variety of Hampshire's attack was too much for them: Smeed plinked Nathan Ellis to mid-on, and Banton was run out at the bowler's end by Mason Crane's direct hit after failing to dive to make his ground. "It's Finals Day, man," Simon Doull fumed on Sky's commentary. "Do you not want it enough to get your clothes a little bit dirty?"

Rilee Rossouw held the key against his old county and started brightly, hammering Brad Wheal onto the roof of the Hollies Stand. But he holed out to deep midwicket off James Fuller and despite Tom Abell and Tom Lammonby's cameos, Somerset never managed to keep the required rate in check.

"I think they got 10-15 more than we'd have liked," Abell said. "We've chased really well through the competition but we obviously didn't quite get it right. We just wanted to build a partnership and tried to do that. We just couldn't quite get our flow with the bat in the second innings and that cost us."

Ellis finished with three wickets, mopping up the lower order, but Liam Dawson's four miserly overs were crucial: they cost only 20 runs, and he could play a key role in the final as the Edgbaston pitch slows up.