Keith Cunningham and Bobby Hillson met in 1950 at a Christmas function organised by the Central School of Design. At the time, she was a fashion student at Saint Martin’s, which was then a separate institution.

Hillson’s career started in the early 1950s, when she began working as an illustrator for Vogue UK, The Sunday Times and The Observer. In 1956, she returned to Saint Martin's School of Art to teach on the fashion diploma course, while continuing to independently produce designs and illustrations. In 1969 Hillson launched her childrenswear brand, with one of her creations being chosen as the Dress of the Year in 1972.

In the late 1970s she founded and developed Saint Martin's MA fashion course, where she was one of the first people to recognise the potential of Alexander McQueen, offering him a place on the course. In addition to McQueen, Hillson's former students include John Galliano, Stephen Jones, Rifat Özbek and Sonja Nuttall.

In 2016, two years after her husband’s death, Hillson organised an exhibition of his works on canvas with the help of curator Stephen Rothholz and graphic designer Mike Dempsey. The show, held at Hoxton Gallery in London from 30th September to 13th October, was well received by public and press and contributed to reviving interest for Cunningham’s art.