Toni Duggan, Jill Scott and Nikita Parris scored in a 12-minute blitz in the second half as Phil Neville’s side booked their place at the finals in France.
The victory put England top of Group 1 with one match remaining, while Wales, who previously occupied top spot, have played all eight of their games.
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At the home of Newport County, England made the breakthrough on 57 minutes when Barcelona's Toni Duggan latched onto a pass from Fran Kirby to score.
Three minutes later midfielder Jill Scott headed home to make it 2-0, scoring her 20th goal in 130 caps.
And it was Parris who wrapped things up on 69 minutes as England profited from a goalkeeping error.
England came third at the last World Cup in Canada in 2015.
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