Recent winner of the U.S. Open, Retief Goosen, posted a 3-under-par 69 to share fourth place with four other players. Goosen is joined at minus-3 by Spaniard Jesus Maria Arruti and trio of Englishman - Matthew Blackey, David Howell and Lee Westwood.
Broadhurst got his round going with a birdie at the par-3 second, but tripped to a bogey at the very next hole. After a pair of pars, the Englishman dropped in a birdie try at the sixth on the South Course at The K Club.
The four-time winner on the European Tour then eagled the par-5 seventh to move to 3 under. Broadhurst remained hot as he converted back-to-back birdies from the ninth to move to minus-5.
Broadhurst faltered to a bogey at the par-3 12th. He ran off five straight pars before birdieing the par-4 18th to get into the clubhouse at minus-5.
'I thought that anything par or better would be a real good effort,' said Broadhurst, a former European Ryder Cup performer. 'I only hit one bad shot and it was a case of hanging on coming in with that right to left wind. My game has been up and down the last four or five weeks, but hopefully it's coming back. Confidence is the thing, really.'
Lafeber got off to a hot start with consecutive birdies from the 10th and moved to 3 under with a birdie at the 13th. The 29-year-old got to 4 under with a birdie at the 16th, his seventh.
However, Lafeber stumbled to a bogey at the 18th. Around the turn, he fought back to birdie the second and fourth to get to 5 under. He tripped to a bogey at the fifth, but atoned for the mistake with a birdie at the seventh. He parred the final two holes to join Broadhurst in the lead.
'It's been a good week for me. I hit most of the greens in regulation, which you need to do around this golf course,' Lafeber said. 'I stayed calm and kept playing well. I had a good talk with my coach and my caddie and they told me just to accept the bad shots and not to push too hard. I know my normal game is good enough for The European Tour and that is what I said to myself at Sunningdale as well.'
O'Hern also began his round on the back nine and started with four straight pars. He got into red figures with a birdie at the 14th. He then closed his opening nine with back-to-back birdies from the 17th to make the turn at minus-3.
The left-handed Australian climbed to 4 under with a birdie at the par-4 fourth. O'Hern picked up his fifth birdie at the par-5 seventh, and closed with two pars to cap a bogey-free round.
'I never looked like dropping a shot,' said O'Hern, who shared second at the Open de France last week. 'I missed only one fairway and one green and gave myself a lot of chances. Mentally I am very patient at the moment, but it's easier to do that when you are playing well. I much prefer tougher conditions. I work my way around a golf course and I love it especially when the wind blows because you have to manufacture a lot of shots.'
Irishman Padraig Harrington posted a 2-under-par 70, where he shares ninth place with Richard Green, Andrew Coltart, Bradley Dredge, Gary Evans, Niclas Fasth and Paul McGinley.
Peter Hedblom, Soren Kjeldsen, Jose Manuel Carriles, Francois Delamontagne, Martin Erlandsson, Stephen Gallacher and Henrik Stenson are one stroke further back at minus-1.
Phillip Price, the defending champion, struggled in his title defense. He stumbled to two bogeys, two double bogeys and three birdies en route to a round of 3-over-par 75.