Wanstead saw their hopes of Vitality Club T20 success shattered by Wimbledon at the South Regional Final.
The sides met at Basingstoke & North Hants, with Herons captain Joe Ellis-Grewal putting the south London club into bat after winning the toss.
Zain Shahzad struck early with the ball, but David Scott hit six fours in an 11-ball 27 before falling to Nabeel Aziz.
And Wimbledon captain Jack Boyle added 85 for the third wicket with Tim Lloyd (25), who fell to Yuvraj Odedra.
Boyle followed for 69 off 41 balls, caught and bowled by Jahansher Akbar, having hit 10 fours, with Odedra claiming three more scalps to finish with 4-25 as the innings closed on 177-8.
Tom Simmons hit 22 off 16 at the start of Wanstead's reply, with opening partner Shahzad adding 21 off 13 as they reached 63-2.
But Haaris Usman and Ali Zeb fell cheaply, before Essex staffer Robin Das departed for 34 off 21 balls to leave the Herons 99-5.
Ellis-Grewal and Aziz followed in the space of three balls, without addition to the total, but Odedra held firm and saw Jonathan Das score 15 off five balls.
The ninth wicket fell with the score on 133, but Odedra managed the strike well with last man Akbar to reduce the target to 14 off the last over.
But it proved just beyond Wanstead as they closed on 173-9, with Odedra unbeaten on 56 from 32 balls, having hit three sixes and five fours.
Swansea beat Birmingham League side Harborne in the other semi-final tie, after Tim Moses scored 62 off 39 balls in their 171-5 and then took 5-32 to dismiss their rivals for 148.
But Wimbledon were convincing winners of the final after dismissing the Welsh club for 122.
They raced to a seven-wicket success with eight overs to spare thanks largely to Nicholas Welch (58 off 29) and Lloyd (44 not out) and will meet North Regional champions Sandiacre Town, of Nottingham, in the national final at Derbyshire on September 17.
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