England piled up 219-1 in an 89-run victory against Sri Lanka on the opening night of the tournament before a nervy four-wicket win over Ireland, in which captain Nat Sciver-Brunt injured her calf.
Since then England have brushed aside Scotland, West Indies and New Zealand to build momentum before the semi-finals.
Opener Danni Wyatt-Hodge is the tournament’s leading run-scorer while Charlie Dean has stood in ably for Sciver-Brunt.
Coach Charlotte Edwards, who was brought in at the start of last summer after the Ashes clean sweep down under, appears to have brought a calm steel to the dressing room.
“I have been so impressed with them,” said Hartley. “They are the best [England] team I have seen for a good few years.
“They seem to have everything covered. I think they have one of the best bowling attacks in the world and with the bat, Danni Wyatt-Hodge is in the form of her life.”
South Africa finished second in Group 1 behind Australia, who beat West Indies on Tuesday to secure their place in Sunday’s final at Lord’s.
The Proteas have beaten England in the sides’ past two semi-final meetings – at the 2023 T20 World Cup and last year’s 50-over World Cup – but were unconvincing through much of the group stage.
