"They spoke together and it was all about my load up," Filer, the 22-year-old Western Storm quick, said. "My timing was all wrong. So it was trying to load up at the same time to get my timing right basically, in simpler terms. It's helped a lot.

"I think it looks a lot different. It didn't take me too long, it took me probably a couple of weeks to get used to it, but a lot of people have noticed it and said how weird it looks, saying they I think I'm hiding a variation, but I'm not.

"It's good for me because it makes me feel comfortable and I'm less likely to get injured as well. So for me, it's really great and then other people notice it as well, which is nice to hear."

The new approach is also helping her to bowl even faster, too. Upon being selected, Jon Lewis, the England head coach, and captain Heather Knight had described her as being among the fastest bowlers in the country. Filer was clocked at 76 mph/123kph during the opening day of the Test, which swung this way and that to be pretty evenly poised at the close.

"I know that I've definitely put on a few yards," Filer added. "It's almost easier to bowl quicker as well. I feel like last year I had to really try and it did hurt whereas now it feels I'm having a really good flow."

Filer thought she had a wicket with her first ball in international cricket when umpire Sue Redfern gave Perry out lbw on 10. But Perry immediately called for a review, which confirmed that she had hit the ball onto her pad. Filer's second ball beat Perry for pace, and, with her 18th delivery, she had formidable Australia opener Beth Mooney out for 33 with a 74mph/119kph delivery that climbed on her and took an edge before flying to Kate Cross at gully.

"I was a bit shocked," Filer said of learning she had earned her maiden senior cap. "I'm not usually lost for words but I didn't really know what to say to Lewy [Lewis] when he told me.

"It's weird. I don't think it sank in until I was on the pitch. So I didn't feel too bad until probably about five minutes before and five minutes on the pitch. Once I fielded my first ball I think I settled down a bit, but it was definitely a bit nerve wracking at the start.

"That's a great start and that's what I want to do as well, so I'm very happy. It's a bit of a surreal experience, but it was a really good day, I'm a bit tired now but I really, really enjoyed it."

Perry, who helped Australia recover from 83 for 2 and close the day on 328 for 7, was impressed.

"I had a really great tussle with Filer the whole time, I thought she was extremely impressive today on debut and brought the game alive at different points," Perry said. "That ball [dismissal] just had my measure, which is which is totally fine. But I really enjoyed today to be out there and to be a part of it."

Sophie Ecclestone, the ICC's No. 1-ranked bowler in both white-ball formats, who is only two years older than Filer but 110 matches more experienced at this level, made life easier for her seam-bowling team-mates, sending down a mammoth 28-over spell - which took in the lunch break and a 90-minute rain interruption - with her left-arm spin, and capturing three wickets, including Alyssa Healy for a second-ball duck.

"She's a bit of a bowling machine," Filer said. "Bowling for two hours, that's pretty impressive. I've never really seen anyone do that before, but she is still standing and she's going strong.

"It's great that she can kind of tie up an end and that she's consistent and we can rely on her. It's a big, big role to fill and she does it so well. It makes the other bowlers at the other end feel comfortable doing what they're doing because I know that she'll go for nothing. So if I go for a for a couple of boundaries she's got my back at the other end, that's really good."

With the second new ball just five overs old, Filer could well be called into action early on the second day, but she was relishing the prospect.

"Now with the new ball we're definitely going to attack tomorrow morning," she said. "It's probably evenly poised at the moment."