Hull and veteran Trish Johnson led the home challenge on day one with excellent four-under 68s, although they were two shots behind Giquel-Bettan after her seven-birdie opener.
The French player started at the 10th and enjoyed a run of three birdies in four holes from the 12th before adding another at the risk-reward 17th to turn in 32.
Giquel-Bettan made her only mistake of the round at the first, but she bounced back with birdies at the third, fifth and sixth and parred safely in to set the early clubhouse target at six under par.
???It was a great day,??? said Giquel-Bettan. ???Yesterday I played the Pro-Am and it was 36 degrees. It was so hot and this morning it was 20, 22C with just a little breeze, so perfect conditions.???
She ended the day with a one-shot advantage over??Ashleigh Simon, Sophie Sandolo, Josephine Janson and Nontaya Srisawang, while the English pair of Hull and Johnson were a further stroke adrift.
Hull reached three under after only six holes and offset a bogey at the eighth with her fourth birdie at nine before picking up one further shot at the 12th in a solid, if frustrating inward half.
“I???m happy because I putted pretty well today,” said the Solheim Cup star. “I just kept coming up short with my irons. I struck it well but kept miss-clubbing myself. I feel like I???m so used to my American distances that now when I???m in a tournament I keep thinking I???m going to hit them a bit further but I don???t.
“I actually played better on the back nine. I gave myself lots of chances but didn???t take them. I lipped out on a few putts for birdies but apart from that I???m taking the positives and looking forward to tomorrow.”
Fellow Britons Melissa Reid and Dame Laura Davies had one-under rounds of 71 to lie in a share of 37th place, a stroke ahead of Amy Boulden, the 2014 rookie of the year.
Davies had only one birdie in her round at the final hole, but she eagled the sixth after holing her approach with a wedge while also rolling in a 30-foot putt for another eagle at the 14th as she bounced back from a double-bogey at 11 and a dropped shot at 13.