Image: Bryony Marks at the piano.
She has really worked her way into the medium over the last decade, and has been continuously employed pretty well since 2010. She has the luxury of working on productions she likes, claiming that the music fails if she is not inspired by the show.
That is a pretty enticing position for directors and producers, but she thinks she is chosen because her emotional response fits the material. The rest is just technique, and the ability to imagine different kinds of sound, rhythms and instruments. That is basically code for versatility.