The pair leads by a stroke over Italian Marco Bernardini and by two over David Howell and Costantino Rocca.
Oldcorn, hot off a win at the Volvo PGA Championship, started in shaky fashion, but ended in a blaze, as the 41-year-old Scott followed up a front-nine score of 1-over 31 with six birdies over his last six holes at the Marriott Forest to close in 6-under 30.
Im very pleased obviously, Oldcorn commented following his round. It was a bit up and down to start with, but on the way home I really felt my swing and my rhythm were back.
Of the windy conditions that prevailed over the grounds of Warwick on Thursday, he added: Im never too upset when the wind is about because if my game is on, I can hit a lot of different shots and I did that today.
Scott likewise found the shots that he needed. Yet, the young Australian would have ended at 6-under had it not been for the long par-3 15th ' it was there that he made his only bogey of the day when he missed a par attempt of some four feet.
I think if you look at the stats I finished last in putting at the Deutsche Bank and close to last at Woburn, so thats where the problem is, Scott claimed. I made one long putt today, but apart from that, I cant remember when I last holed one of that length.
Its technical so I just have to work on my technique a bit, he added. I speak to Butch Harmon and I get to speak to Tiger Woods about my putting a lot. They all tell me the same thing ' I swing with my putter head a bit shut so Ill just need to work a bit harder on that.
While Scott and Oldcorn cruised around nicely on Thursday, two-time defending champion Darren Clarke did not have such a good time of it, as the big Northern Irishman struggled with a 2-over 74.
It was difficult but I didnt hit it that badly, he claimed. But I putted shockingly badly. The ball wasnt moving on the greens but with their pace and the wind as gusty as it was, it was very difficult to get the line right.