If England had sent Emma Lamb in to bat at any position, she reckons she would have tried to grab her chance with both hands. That the opportunity came knocking in her favoured opener’s role and resulted in a century as England swept South Africa aside by five wickets in their opening ODI made it “amazing”.

Making just her fourth international appearance, Lamb’s 97-ball 102 accounted for much of England’s successful pursuit of 219 in Northampton to take a four-points-to-two lead in the multi-format series, with two more one-day matches and three T20Is to play.

A fortnight ago, Lamb made 38 on Test debut opening alongside Tammy Beaumont as the sides drew in Taunton. That followed a second-ball duck during the third ODI against Australia during the Ashes in February and she wasn’t required to bat as England opened with Beaumont and Danni Wyatt in their nine-wicket win against Pakistan at the World Cup.

“You always want to prove yourself, don’t you?” Lamb said pitch-side at Wantage Road on Monday, when asked about those earlier ODIs. “I suppose that was kind of like a little drive, a little thought in the back of my mind but I feel like any opportunity that I got, even if it wasn’t opening, I would have taken it and tried to do the best I could with it.”

Wyatt has moved up and down the order as England wrestled with an opening conundrum. She replaced Lauren Winfield-Hill at the top during the World Cup and scored a century in the semi-final against South Africa. Here she dropped down to No. 6 and struck the winning runs with an unbeaten 14 off five balls after Lamb had done the heavy lifting alongside an explosive 55 off 36 by Nat Sciver.

Heading into the Test match, England head coach Lisa Keightley had said she was keen to see what Lamb could do as an international opener, having played the majority of her domestic and regional cricket there, and she acquitted herself well in a 65-run stand with Beaumont.

Here Lamb took a lead role after Beaumont fell in the third over and she ran with it.

“I felt pretty comfortable,” Lamb said. “I went in today knowing my role and having the coaches and my team-mates back me, I felt pretty happy with what I needed to do.

“When you lose an early wicket there’s a little bit of pressure on me but I was still wanting to play my game and not change anything. When I got past the 50-mark, I was really happy but when I got to 100, obviously I was over the moon.”

She played beautifully to the off-side and when she brought up her ton with an open-faced drive off Nadine de Klerk, Heather Knight, her captain was at the opposite end of the pitch, with a fist-pumping hug at the ready and looking almost as thrilled as Lamb until the latter removed her helmet and turned to the changing room with a beaming smile and arms raised aloft.

“She was just so buzzing for me,” Lamb said of Knight. “It’s a little bit emotional. I think when anyone gets a hundred it can be like the best thing in the world and a little bit emotional but yeah, it was very nice to be out there with the skipper and get a hundred and hug her.”

Heading into the second match in Bristol on Friday, Lamb indicated England were keen to ride a wave of positivity against a South African side which beat them in the group stages of the World Cup and had come into this match wanting to atone for their semi-final defeat.

That the match wasn’t particularly close after Sciver and Katherine Brunt had combined to take seven wickets between them to contain their opponents did not come as a surprise to her either.

“I’m not surprised because I think it was a big mindset thing for us,” she said. “We just wanted to be really positive and our bowlers did really well today on a very good wicket.

“We just wanted to be positive with the bat and when we play our best cricket, we can easily dominate and win easily like we have done.”