The 38-year-old Frenchman carded an opening round of 63 to finish seven under par, having recorded an eagle at the seventh before acing the par-3 13th.
A dropped shot at the 10th was the only blemish on Havret’s scorecard.
Sheffield’s Danny Willett is just two shots back after a 65, John Parry (Harrogate) carded a 67, Matthew Fitzpatrick, of Sheffield, a 69 and Hull’s Richard Finch a 70.
Lasse Jensen of Denmark is just a shot further back of Havret, with Tyrrell Hatton missing out on the overnight lead after a poor final hole. The Englishman was at eight under but found the water on the 18th and hit a triple bogey to leave him down in a group at five under.
Willett had four birdies in seven outward holes, a fifth at the 15th coming on the back of an eagle 3 at the 559-yard par-5 14th.
However, he shed shots at holes 11 and 16.
Parry was out in three under with a trio of birdies, and had a similar outcome at holes 11, 13 and 15. But he dropped shots at 12, 16 and 17.
Fitzpatrick was out in one over after a birdie at three preceded bogeys at four and six.
He also bogeyed the last, but his card was pepped by an eagle 3 at the 516-yard par-5 14th.
Finch, like Parry, covered the outward stretch in three under with three birdies, and went four under at the 14th.
But he will want to make amends today for his clumsy finish which saw him double bogey both 16 and 18.
Willett, who has risen to a career-high of 32 in the world rankings, was pleased with his opening.
He said: “They’ve tinkered with the golf course again this year so it’s playing fairly tough, so anything under par was a decent score and 65 is very pleasing.
“’It sets up quite nicely for me here. It’s a good fun golf course, and a good fun week. I’ve got my family here with me, so it’s been a nice week off the course and, so far, a nice week on it as well. Long may it continue.’’
Lee Westwood finished his round two under par and tied for 39th despite a poor start.
Michael Hoey matched Havret’s ace, the 39th hole-in-one on the European Tour this season, equalling the all-time high set in 2006.