England had responded from defeat in the Test at Trent Bridge and losing the opening T20 at Edgbaston to pull off a three-run win in a thrilling finale at the Oval on Wednesday.
Heather Knight’s side continued that momentum to restrict Australia to 155 for seven at Lord’s, and then Capsey led the chase of a Duckworth-Lewis-Stern revised target of 119 in 14 overs to win the T20 series and reduce the multi-format deficit to 6-4 ahead of the deciding one-day internationals.
Australia, put into bat after Knight had won the toss for the first time in this Ashes, made a swift start in front a crowd of 21,610, another record attendance.
Captain Alyssa Healy and Beth Mooney hit 10 off the first over from Charlie Dean and Healy was then dropped when on 13 off Nat Sciver-Brunt, the all-rounder unable to take a caught-and-bowled chance down to her left.
Dean made the breakthrough with the first delivery of the fourth over to trap Healy lbw for 16 with a length ball.
England took another wicket in the seventh over when Tahlia McGrath (10) sent a short ball from Danielle Gibson to Capsey at mid-off, leaving Australia at 37 for two.
Mooney sent Sarah Glenn for three consecutive boundaries in the eighth over, and Australia pushed on past 100 before rain took the players off during the 15th over, but it proved only to be a short delay.
Ellyse Perry again set about the England bowlers, racing to 27 off 21 deliveries. Lauren Bell eventually had her lbw for 34 in front of middle, which was not able to be reviewed because of a technical problem with the DRS. Harris (25) was run out going for a second run off the final delivery, as Australia finished 155 for seven.
During the interval, the covers came out as rain again set in which delayed the restart until just after 9pm. As a result, England’s run chase was revised to 119 from 14 overs, with four of those comprising the powerplay.
England’s momentum was halted at the end of the fourth over when, after a run of boundaries, Wyatt edged Megan Schutt behind to depart for 26 off 15 balls.
Australia struck again with the next delivery when Dunkley (nine) sent Darcie Brown’s opening delivery straight up and was caught by Jess Jonassen at backward point to leave England reeling at 39 for two.
Capsey sent Jonassen over deep midwicket for a huge six as England passed the half-century mark, while Sciver-Brunt hit Sutherland for another boundary. Capsey then had a let-off when Georgia Wareham failed to hold a diving catch in an expensive ninth over from Gardner.
Capsey’s onslaught continued as she smashed Schutt for a huge six and then a four – but was then out to a fine catch from Gardner from a shot over deep square leg to fall just short of her half-century.
Just when England looked to be cruising to victory, Sciver-Brunt was bowled by a flatter delivery from Wareham for a run-a-ball 25.
England were left needing two off the final over from Jonassen – who promptly trapped Knight (six) lbw with the first delivery. Gibson, in just her third game for England, showed nerves of steel to reverse sweep Jonassen for a boundary and secure another dramatic victory.
Additional reporting by PA Sport.
