Booth, also aiming for a first victory on home soil, led on six-under-par before taking a double bogey at her last hole, the par four 18th.
“I just pulled my second shot a little bit and then it was nicely plugged right up the face of the bunker, so I decided to take an unplayable because I could see myself hacking at it,” she explained. “I did that and dropped it back, where it plugged a little bit again and then I hit it over the green and chipped and then holed my putt for six. We’ve still got two more days to go so I could make that up in the next two days hopefully. I played flawless for the rest of the day.”
Rigon attributed her round to improved putting. “I changed my putting grip and it’s working,” she said. “I had 27 putts today which is much better.”
With tougher weather conditions forecast for the weekend, Zackrisson and Mills have the advantage that they are both recent tour winners.
Zackrisson claimed her maiden tour title at the Ladies Spanish Open in April, while Mills took last year’s S4C Wales Ladies Championship of Europe, played at Machynys Peninsula G&CC, a similar golf course.
Mills said: “I started with a three putt on the 10th hole and then I had another one on the 15th, but they were the only two bogeys I made all day, so I was really happy to sort of keep on the fairway and keep it on the greens. I missed a few good chances, but at the end of the day 68 was fantastic stuff.”
Zackrisson added: “The wind was nice to us; the weather was perfect, I can’t ask for better weather in England.”
The title holder Becky Brewerton shot a two over par 74 to finish the day six shots off the lead.