The New Zealand netball coach Ruth Aitken says three out-of-season Tests over five days in England put a lot of pressure on a squad depleted by injuries.
The Silver Ferns trailed until the third quarter in London before completing a series sweep with a 47-40 win.
Aitken says the likes of the captain Casey Williams, midcourter Laura Langman and goal shoot Irene van Dyk responded well to a real challenge.
She says England's closing the gap with New Zealand and Australia and so are Jamaica after sharing their series with the world champions in the Caribbean.