Some of her early software is on display in the Science Museum in London. But Mrs Shirley has one contemporary distinction: when women in computing are under discussion, hers is always the first name mentioned (as is the story of how she changed her name from Stephanie to make sure her bids for assignments got to the interview stage). In so far as the industry has its icons (if not legends), she is among them.
Comfortably taking tea amid the fusty male formality, manners and mores associated with a gentleman's club, Mrs Shirley shows few signs of settling into a quiet retirement on leaving the FI Group, of which she was chief executive for 25 years. Standing on the edge, she has a clear view of the way the industry ought to be going. Not surprisingly, it features a strong role for women and the 'feminisation' of management skills.
This has nothing to do with wearing scent and frilly blouses in the boardroom and everything to do with fusing two personae which have traditionally constituted the male working environment: the hard-nosed professional with their mind solely on the job, and the individual with domestic responsibilities.
Not only can they be combined, Mrs Shirley believes, but organisations can benefit from an ethos with more 'feminine' input. 'Management in the Nineties is now less by command and control and more by building team work and empowering individuals,' she says. Once the culture is altered, she adds, there is no looking back.
Mrs Shirley established her own culture at FI, now a company with a pounds 35m turnover, based at Hemel Hempstead. Its roots lay in her own experience of wanting to be a wife, a mother and a fulfilled professional. Rigid hours, combined with the attitude that home should never take sway over work and that management was done only in a prescribed way, prevented this. With pounds 6, spent on stationery, and use of her dining room table in her home just outside Chesham, Buckinghamshire, she set up FI in 1962.
The job she had left was with ICL, developing software along with a minor degree of management. She liked the organisation, had been allowed to drop to four days a week - a rare concession - but, she says, 'as soon as I stepped outside the technical role, I got my knuckles rapped. Even with this rather splendid employer I realised I wasn't going to be able to do some of the things I wanted to do. I decided that the only way I could get the flexibility and working ambience I wanted was to form my own company.'
Like most entrepreneurs, she had a vision and ability but was short of money. Also like many entrepreneurs, she risked her house by taking out a second mortgage.
FI's ethos was to take advantage both of technical advances to encourage working at home for flexible hours, and of the fact that software no longer needed to be developed on site. 'The Sixties in the FI Group was part of the emancipation of women,' Mrs Shirley says. 'We were the first women going through the industry.'
Unusual in Britain, contracting out was already established in the United States, and the Mars company was one of her first customers. In the UK, however, there was little recognition for service industries that offered only people and their skills rather than manufactured goods, and getting the business off the ground was not easy.
Part of Mrs Shirley's strategy for survival was to change her first name from Stephanie to Steve. That way, she found she could get her foot through the door by sidestepping prejudice. But her determination to succeed is more deeply rooted in her background. At the age of five, she was one of 10,000 unaccompanied children shipped out of Germany as refugees and had an immigrant's fervour to prove she was worth her survival. Raised by foster parents in the Midlands, she wanted to be a mathematician.
'That sort of childhood brings entrepreneurial drive,' she says. 'It's the only thing common among immigrants.' She did an honours degree in maths while she was working. 'Difficult though it was, it did mean that in my early twenties I had not only academic qualifications but work experience, and it did differentiate me from my peers. If you then work 12 hours a day, seven days a week, you soon pull yourself in front of people who are academically superior.
'I have lived the fact that I was saved while a million children died and I have needed to justify my survival. It's called survival guilt. The laissez-faire attitude of more established people doesn't give them that sharpness and focus to succeed in business.'
FI grew into a company with 1,000 people, specialising in computing services and training. It is owned by its staff and has several 'work centres' near motorways in different parts of the country. They are open 24 hours a day, seven days a week. Work is measured in time but is not subject to rigid hours.
Lack of confidence rather than lack of fervour is now women's biggest handicap, she says. 'It manifests itself in low career aspirations, apparent reluctance to innovate or take on leadership roles and an unhealthy willingness to accept subservient positions with little thought of reward. For many women, doing the job well is what matters most. Being seen to do a good job is seldom regarded as important. Neither is being seen to be available for promotion, nor even just being seen to network with other people. They either lack such political skill or find it distasteful and refuse to 'waste time', to everyone's disadvantage.'
As a director of Tandem Computers and of the Atomic Energy Authority (and as founder of the Kingswood Trust, a non-profit-making body that she established to set up independent homes with carers for mentally handicapped people, such as her son), she wants to use her profile to keep proselytising.
'Those of us who have achieved some prominence in one way or another have to be prepared to stand up and be counted,' she says. 'There are far too many women who cannot see a parapet without ducking behind it.'