He is joined in the lead by Pasi Purhonen (68), Massimo Florioli (69), Jean- Francois Lucquin (69), Simon Dyson (70) and overnight leader Carl Suneson (73). Alessandro Tadini also carded a 67 to take seventh place at 2-under-par 211.
Geall, who turns 36-years-old tomorrow, was steady to start with seven straight pars on the Val Course at Aa Saint Omer Golf Club. He picked up his first birdie at the eighth, then posted six consecutive pars from there.
Down the stretch Geall caught fire. He dropped in a birdie at the 15th and came right back to birdie the 16th. After a par on 17, he closed his round with a birdie at the last.
'I played solid all day, with 14 pars and four birdies,' said Geall. 'I had 16 greens in regulation and the two that I missed I got up-and-down well, so I am very happy with that. It just came together that little bit more than it had at the end of the round and I managed to take advantage.'
Purhonen spread a bogey and a birdie over his first six holes. He then dropped in back-to-back birdies from the eighth to get to 2 under. He picked up another birdie at the 12th before faltering to a bogey on 14. He atoned for that mistake with a birdie on 16 for a share of the lead.
Florioli picked up consecutive birdies from the third to move to 3 under. After he bogeyed the eighth, the Italian ran off three consecutive birdies from the 10th to climb to minus-5. He stumbled to back-to-back bogeys from the 13th to fall back to the pack. He parred his final four holes to remain in a share of first.
Lucquin made a run midway through his front side as he posted three birdies in a row from the fifth to get to 4 under. He faltered to a double bogey at the eighth, but erased that error with back-to-back birdies from the 10th.
'That happened just after I had been plugged in the bunker on the eighth and had ended up with a double bogey,' said Lucquin of his tee shot off the ninth tee, which bounced off a tree to remain in bounds. 'I was trying to kill the ball and got very lucky to escape with a par. I am happy to be in among the leaders and feel good for tomorrow.'
The Frenchman climbed to minus-5 with a birdie on No. 14. Lucquin then dropped shots at 16 and 17 to fall into the logjam for the lead.
Dyson traded a birdie and a bogey at the third and fourth. He rose to 4 under with birdies at the ninth and 11th. After bogeys at 12 and 13, Dyson birdied the 14th before parring the final four holes.
'I do fancy my chances,' Dyson said. 'I'm playing nicely and if I can get to grips with the greens and keep making the birdie chances then I will be there or thereabouts. My positional play has been really good, using my head and managing the course really well.'
Suneson led by one stroke entering the round. He traded three bogeys for three birdies over a six-hole stretch from the fourth. He tripped to bogeys at the 12th and 13th to fall back to minus-3. He parred his final five holes to share first place.
First-round leader Kyron Sullivan struggled to a 4-over 75 Saturday. He slid to even-par 213, where he is joined by Didier de Vooght, Philippe Lima, Titch Moore, Johan Skold, Benn Barham, Stephen Browne, Murray Urquhart and Tom Whitehouse.