IT was another day that summer bypassed on the Ayrshire coast yesterday, which made Suzann Pettersen's second-round 69 well worthy of the halfway lead in the Ricoh Women's British Open at Turnberry.

The wind howled and the rain poured and it was an altogether miserable day for playing golf, not to mention the spectators. But Pettersen, out before 7 am, managed to compile an impressive four-birdie round and could then sit back and watch her rivals struggle, and ultimately fail, to keep pace.

In the end, the Norwegians seven under par 137 total was good enough for a two stroke advantage, with New Zealand's precocious world No.2 Lydia Ko among the nearest challengers.

It was towards the end of last year that Pettersen, a 33-year-old with two majors already to her name, switched high profile coaches. She moved on from David Leadbetter to Butch Harmon, the man who was in charge of Tiger Woods swing when the great man first turned professional.

Pettersen couldn't be happier with the changes Harmon, who also commentates on Sky TV, has made to both her technique and her attitude and she is now looking forward to a golden patch in a career that has been impressive but also hampered by injuries.

"I always felt I had a different gear in my body," said the 2001 Ladies European Tour Rookie of the Year. He has made changes and it is just a much easier move. I don't feel like the swing thoughts change from day to day.

"Its very consistent. Its nice to have somebody that can really push me. Butch has pushed me quite a lot and I feel that some of my best golf is still ahead of me.

"I thought it would be good to play through [next years] Olympics, but I now have a lot of more goals. I want to be the best that I can be."

Last week, she finished runner-up in the Aberdeen Asset Management Ladies Scottish Open at Dundonald Links and four birdies and just one bogey was another good score in the locker.

Pettersen's first major was the 2007 LPGA Championship and she added the Evian Championship two years ago. She's got a decent record in this Championship with top five finishes in the last two years.

"I'm getting older and wiser, she suggested with a smile. You learn something every year and that is what is so great about this game.

"It was really tough out there today but I played really solid. I felt I was in control of everything. It was good to play in the Scottish Open last week. It is the first time I have done that and it has helped my game adjust to this type of golf.

It wasn't too good a day for the Scots. Seven started and only two, the evergreen Catriona Matthew and qualifier Carly Booth, survived a cut that fell on four over.

Matthew made it with a shot to spare after a 77 and Booth was on the final mark having also shot five over in the miserable weather.

Matthew, who famously won the title at Royal Lytham and St Annes in 2009, played alongside Pettersen and was truly impressed.

"Suzann played beautifully," praised the North Berwick 45-year-old. "She controlled the ball so well and made a lot of really good putts for par."

England's Mel Reid was the leading British player on one-under-par 143, a second-round 70 boosting her hopes of regaining her place in the European Solheim Cup team to defend the trophy in Germany next month.

The 27-year-old, who was top amateur at the 2007 Women's British Open at St Andrews, had four birdies in the worst of the afternoon weather.

Ko, who opened with a six-under-par round, was another who was mightily impressed by Pettersen's effort.

"Today was like playing a different course," said the teenager. "I knew I wasn't going to shoot 66 again and it was going to be a day for grinding it out. We were tried to hide behind the signs for shelter. Suzann must have played great."

World No.1 Inbee Park wasn't too delighted with a 73, but the South Korean is still well in the hunt on two-under par, three ahead of the 2013 Champion from St Andrews, Stacy Lewis.

Michelle Wie was heading for a missed cut but she didn't make it past the 13th hole. At 10 over for the round and 14 over for the Championship, last years US Women's Open Champion retired with an ankle injury.

Last year's victor Mo Martin also missed out. After a promising opening 70, the American slumped to a second day 80 to miss out by a single shot.