The 28 year old, who won the weather-affected Madeira Islands Open "“ Portugal last year, has made just four cuts all season, but turned the form book on its head with a stunning round of 65.
Two closing birdies gave Brooks some breathing space at the top of the leaderboard, with the Irish duo of Shane Lowry and Graeme McDowell, American Ryan Palmer and defending champion Justin Rose amongst those in a share of second place on eight under par.
Gullane Golf Club was again bathed in afternoon sunshine, and Brooks took full advantage of the benign conditions with an eagle and four birdies.
He said: "I've played really solid for the past two days, and not missed many shots at all. Other than the bogey on the fourth hole, where I hit a poor tee shot, everything else was really good. I had ten to 12 feet putts for birdie all day, and whilst I didn't manage to make that many of them it's still a great score.
"I've been playing nicely for the past three weeks now. I just missed the cut in Germany, but played some nice golf. I played well again in France, just made a load of silly mistakes. But I've managed to cut them out so far this week, and it's working out very nicely.
"It's been hard this season, missing so many cuts. It does get you down, but it only takes one good week out here to turn it around and hopefully that's what I'll have."
Lowry, McDowell and Rose both signed for rounds of 66 to move in contention to land a first European Tour victory of the 2015 campaign.
The leading Australian and only one to make the cut is John Senden who is at 4 under par and seven shots from the lead but just four out of second position.
Second Round Scores (83 players made the cut on 138)
129 D Brooks (Eng) 64 65,
132 R Palmer (USA) 67 65, J Carlsson (Swe) 65 67, G McDowell (Nir) 66 66, J Rose (Eng) 66 66, S Lowry (Irl) 66 66, M Nixon (Eng) 65 67,
133 R Cabrera-Bello (Esp) 67 66, R Finch (Eng) 65 68, T Fleetwood (Eng) 67 66, R McEvoy (Eng) 66 67, E Grillo (Arg) 66 67,
134 M Kieffer (Ger) 69 65, G Stal (Fra) 66 68, G Havret (Fra) 66 68, J Luiten (Ned) 71 63, S Benson (Eng) 65 69, P Lawrie (Sco) 67 67, A Johnston (Eng) 67 67, M Kuchar (USA) 66 68, M Fitzpatrick (Eng) 67 67, R Fowler (USA) 66 68, M JimÃƒÂ©nez (Esp) 69 65,
135 R Knox (Sco) 67 68, R Fisher (Eng) 70 65, Y Yang (Kor) 68 67, C Tringale (USA) 68 67, B Martin (USA) 69 66, J Walker (USA) 65 70, J Van Zyl (RSA) 69 66, M Hoey (Nir) 70 65, B Grace (RSA) 69 66, R Jacquelin (Fra) 68 67,
136 J Senden (Aus) 68 68, V Dubuisson (Fra) 70 66, M Madsen (Den) 68 68, T Jaidee (Tha) 67 69, R Rock (Eng) 69 67, M Siem (Ger) 69 67, A Sullivan (Eng) 68 68, P Harrington (Irl) 68 68, F Zanotti (Par) 69 67, P Oriol (Esp) 67 69, E Pepperell (Eng) 70 66, J Garcia Pinto (Esp) 67 69, L Donald (Eng) 69 67, D Drysdale (Sco) 71 65,
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