Jean Bird
From the Women in Aviation site:
"It wasn’t until 1952 that the first female RAF pilot, Jean Bird, a reservist, was given her full set of wings. By this time she had been flying for 20 years, had over 300 hours on 90 aircraft types and had a Senior Commercial Pilot’s licence. In fact she had more experience than most of the instructors who trained her for her wings."
She is mentioned in 'Spitfire Women' by Giles Whittell and was an ATA ferry pilot.