Shirley founded, with a capital of £6, the software company Freelance Programmers, (later FI, then Xansa since acquired by Steria and now part of the Sopra Steria Group). She wanted to create job opportunities for women with dependents, and predominantly employed women, with only 3 male programmers in the first 300 staff, until the Sex Discrimination Act 1975 made that practice illegal. She adopted the name, Steve, to help her in the male-dominated business world. Her team’s projects included programming Concorde’s black box flight recorder.

She served as an independent non-executive director for Tandem Computers Inc., The Atomic Energy Authority (later AEA Technology) and The John Lewis Partnership.

Shirley retired in 1993 at the age of 60 and has since focused on her philanthropy.