As many have stated, it wasn't really "SOLO".
Quote from BBC - "Some early reports suggested it was a solo flight - Ms Curtis-Taylor was the only pilot to fly the vintage bi-plane, but she had a support team of engineers travelling with her in a separate aircraft, as well as a camera crew, who would sometimes sit in with her."
Tracey Curtis-Taylor finishes UK to Australia biplane flight - BBC News
So regardless of a support aircraft with engineers and another POB, still a great achievement.