England 157 for 6 (Dunkley 44, Knight 43, Matthews 1-19) beat West Indies 140 for 8 (Williams 38, Dean 4-19) by 17 runs
Offspinner Charlie Dean followed up her 3 for 22 in the second T20I with her career-best figures of 4 for 19 in the third match against West Indies to help England seal the five-match series.
England made three changes to their XI from the second T20I, bringing Nat Sciver, Amy Jones and Sophie Ecclestone in for Dani Wyatt, Katherine Brunt and Lauren Bell. West Indies, meanwhile, brought in Trishan Holder and Sheneta Grimmond.
Sophia Dunkley and Lauren Winfield-Hill opened for England and got off to a strong start after opting to bat, putting up a 60-run stand. Dunkley was the more aggressive of the two, hitting six boundaries on her way to a 31-ball 44. Afy Fletcher drew first blood for the hosts, bowling Winfield-Hill for 24. Sciver then joined Dunkley at the crease and hit two boundaries before falling for 13. West Indies further dented England with two wickets in the 14th over, first removing Dunkley with a run-out and Grimmond then having Jones caught.
Heather Knight then helped rebuild with a 27-ball 43 which was laced with five fours and a six before falling in the 19th over to Hayley Matthews. England scored 10 runs off their last over to take the total to 157 for 6.
Matthews helped West Indies start positively in the chase, but Aaliyah Alleyne's stay at the crease was short-lived, with Dean dismissing her for a five-ball 3. Dean then produced a double-wicket maiden in the eighth over, dismissing the well-set Matthews for 35 and Shemaine Campbelle for a duck. Rashada Williams and Holder tried to resurrect the innings with a 40-run stand but this time Ecclestone had the latter bowled to break their momentum. After Alice Davidson-Richards dismissed Fletcher for 6, Dean returned to pick her fourth wicket of the day, getting Kycia Knight bowled.
Ecclestone then removed Williams, West Indies' top-scorer on the day, for 38. West Indies needed 22 off the last over but they could score just four runs, falling 17 short.
ï»ż"On the bowlers, we've obviously mixed up the team a little to offer opportunities and work out a bit about a few different players and someone like Charlie Dean has really come in and grasped hers," Knight said. "We're so lucky we've got such depth in the spin department.
ï»ż"I don't think we're too far away from knowing our best team is and knowing potentially what that T20 World Cup squad looks like. It's all been a bit of a fact-finding mission and getting to know a few people and how they work in slightly different places.
"In T20 it's all about trying to find the boundaries and play to your strengths and I felt on that wicket that my strengths were being a bit funky and hitting square of the wicket so it was nice to contribute to a team win and nice to feel in good form."
West Indies head coach Courtney Walsh remained positive despite the series loss.
"The effort we've shown in the last two games, in particular this one is very pleasing," Walsh said after the match. "It's also good that we've got some youngsters around who are showing the fight. We're trying to create a different team culture and approach and learning is taking place all the time. It's a loss in terms of the series but I am pleased with what I am seeing with the bigger picture of what lies ahead for the tri-series [against South Africa and India] and [T20] World Cup."
The fourth and the fifth match of the series are scheduled to be played on December 18 and 22 respectively in Bridgetown.
