On 26 August 1963 she flew an
English Electric Lightning T4 to Mach 1.6 (1,262 mph) after convincing
the Air Minister to let her fly it with
Squadron Leader Ken Goodwin as her
check pilot, and so became the first British woman to break the
sound barrier. She also established by this flight a world
air speed record for women.
[6]
I suspect you are right. here is a direct extract from Wiki