Southern Vipers 187 for 7 (Windsor 47*, Norris 40*, Gunn 3-31) beat Northern Diamonds 183 (Campbell 60, Adams 4-35) by three wickets
Emily Windsor and Tara Norris staged a late rally as Southern Vipers stole victory from Northern Diamonds in a dramatic Rachael Heyhoe Flint Trophy Final at Wantage Road.
Vipers looked for all the world like they would come up short in their pursuit of 184 when Katie Levick, who took 1 for 20, and Jenny Gunn, with 3 for 31, reduced them to 109 for 7.
However, Portsmouth-born Windsor scored an unbeaten 47 and Norris - who had earlier returned 2 for 36 - was 40 not out to trump the Diamonds with an unbeaten stand of 78 as the reigning champions sneaked home by three wickets with two balls to spare.
All this came after Ami Campbell's 60 - her second half-century in four days - dragged Diamonds from 116 for 8 to 183 all out, Vipers captain Georgia Adams taking 4 for 35.
It meant more heartbreak for Diamonds, who lost to Vipers in last year's final and who were bridesmaids at the Charlotte Edwards Cup showpiece earlier this month.
Diamonds sent Linsey Smith in to open, but hopes that she would pinch-hit proved unfounded, though Hollie Armitage was first to go, bowled by Paige Scholfield.
Smith limped to 31 from 65 balls before becoming the first of Adams's victims, sparking a collapse where three wickets fell for a single.
Bess Heath struck the first boundary for 11 overs before Norris trapped her lbw, replays suggesting the ball pitched outside leg stump. Another collapse followed, four wickets tumbling for four runs, and at 116 for 8 Diamonds were in dire straits.
Campbell though refused to go quietly, striking four boundaries to reach 50 in 63 balls and by the time she holed out in the final over the last two wickets had mustered 67.
Their total of 183 looked worth more when Beth Langston bowled Adams and Ella McCaughan, both for nought, to leave Vipers 6 for 2.
Maia Bouchier, released from the England squad to play in the final, struck the game's first six - an effortless pull over square leg - but Phoebe Graham removed Georgia Elwiss caught behind.
Bouchier forged on, taking two fours from one Graham over only be stumped by Heath off the spin of Levick, who in company with Smith slowed the run chase to a crawl.
With the pressure mounting, Jenny Gunn castled Gaby Lewis, before having Scholfield stunningly caught by Armitage and trapping Carla Rudd first ball.
But Norris saved the hat-trick and so began the match-winning stand.
"A dramatic game of cricket with a lot of ups and downs," Norris said. "I thought we bowled really well at the start and we knew it was an achievable total to chase down.
"When I walked out I just said to Winny [Windsor] 'we've got to take it deep, if we bat the 50 overs we win the game'. So it was about holding our nerve just that little bit longer, playing our usual cricket, nothing high risk. I guess it was just pure desire."
Gunn said: "I don't really think it should have got that close with just two balls left and that just shows how well we bowled, but also it's annoying they had a 78-run partnership at the end.
"It's frustrating to not win a final, but what can you do? That's cricket and why we play sport. It's not as if we didn't give it everything, I'm proud of all the girls."
Emily WindsorTara NorrisJenny GunnGeorgia AdamsNorthern DiamondsSouthern VipersDiamonds vs VipersRachael Heyhoe Flint Trophy