|Third Royal London Twenty20 international, Derby|
|England 176-6 (20 overs): Ecclestone 33 (12), Wyatt 30 (25); Mlaba 3-22|
|South Africa 138-6 (20 overs): Brits 59 (57); Kemp 2-18, Ecclestone 2-24|
|England won by 38 runs; won multi-format series 14-2|
Sophie Ecclestone starred with bat and ball as England completed a series clean sweep with a comprehensive 38-run victory against South Africa in the third Twenty20 at Derby.
The 23-year-old top-scored with a career-best 33 not out from 12 balls to help England post an imposing 176-6.
She then took 2-24 with the ball as South Africa struggled in reply.
Tamzin Brits showed resistance with 59 but the hosts could only limp to 138-6 from their 20 overs.
The win means England have won all six white-ball matches in the multi-format series to wrap up a 14-2 victory before the start of the Commonwealth Games on Friday.
After the in-form Sophia Dunkley fell to the first ball of the match, 17-year-old Alice Capsey hit a spritely 25 from 17 balls as England's aggressive approach saw them go past 50 in the power play - while losing two wickets - for the third successive match.
A career-best 3-22 from Nonkululeko Mlaba threatened to reel England in at times but Ecclestone's lively cameo, including 26 runs in the final over that featured two huge sixes, lifted them to a hefty total.
Freya Kemp, the second 17-year-old in the England side, took 2-18 on her international debut as South Africa never looked like threatening that score.
England end series in style
Despite already having won the series, England could not afford to take this match lightly with their Commonwealth Games opener against Sri Lanka just five days away.
They made the worst possible start when opener Dunkley, who has a century and two 50s in her last five white-ball appearances, was dismissed first ball - the first time England have lost a wicket with the first ball of a women's T20 international.
That prompted England to promote Capsey up the order and she responded with a brief but sparkling innings that included four successive boundaries - all in different areas of the pitch - before being dismissed by Masabata Klaas.
That set the tone for the rest of the innings as England continued to score runs quickly despite losing regular wickets, with South Africa's cause hampered once again by several misfields.
Maia Bouchier, who hit 18 from 17 balls, was the victim of a bizarre dismissal when she was run out after failing to get back in her crease - though replays showed she would have been dismissed caught behind anyway had South Africa opted to review.
It was the world's number one spinner Ecclestone, coming in at number eight, who then dragged England up to an impressive total, smashing three fours and two huge sixes as Klaas went for 26 in the final over of the innings - the joint second-most runs scored in an over in women's T20 cricket.
Nat Sciver once again stood in as captain for the injured Heather Knight, who missed out as a precaution after having an injection for a hip problem, with Knight later telling BBC Sport she was "hopeful" of being fit for England's Commonwealth Games opener.
South Africa limp to another defeat
England made a fine start with the ball as Izzy Wong dismissed Lara Goodall with a beautiful in-swinging delivery that cleaned out middle stump in the first over of South Africa's reply.
That brought Brits to the crease, playing in her first match of the tour in place of South Africa's captain for this tour Sune Luus, who fell ill on Sunday evening.
The tourists were already without all-rounder Marizanne Kapp, who had to return home for personal reasons, and regular captain Dane van Niekerk, who missed the tour with an ankle injury, and those absentees were keenly felt.
Brits' defiant 59 from 57 briefly threatened a successful chase but no South Africa batter could stay with her long enough to keep the run rate in check.
Opener Anneke Bosch became Kemp's first wicket in international cricket when she was stumped after some fantastic glovework by wicketkeeper Amy Jones.
Ecclestone then took the key wicket Laura Wolvaardt for 13 to all but end their resistance, with Brits eventually holing out to Ecclestone in the deep for Kemp's second wicket as their innings ended in timid fashion.
'There's a real buzz about the squad' - reaction
Player of the series Sophie Ecclestone to BBC Sport: "When I come into bat I have one job - hit sixes! It came off tonight. I was glad to get some runs. I want Katherine Brunt's spot at seven when she retires so that's the aim long term.
"We are so excited for the Commonwealth Games. We have such a good squad now. There's a real buzz about the squad. Competing for a gold medal at home, it doesn't get much bigger than that."
England bowler Katherine Brunt: "Alice Capsey was 10 days fresh to the world and Freya Kemp wasn't even born when I made my debut! The youngsters keep things fresh.
"Now it's on to the Commonwealths. Last time I had a gold medal was the World Cup in 2017. A medal tournament sounds really cool. I never thought I'd be around for the Commonwealth Games, so it's exciting."
Former England spinner Alex Hartley: "Sophie Ecclestone's innings took the game away from South Africa. If you discount her innings, and that brutal last over, it might have been much closer as a contest. It's been a tough series for South Africa."