Such a view is perhaps inevitable from somebody who seems to have fought all her life against pigeon-holing. Announcing her appointment earlier this month, NatWest drew attention to her knowledge and experience of strategic management and the small business sector. But that does not really cover the half of it.
For more than 20 years, she has taught at leading educational establishments in Britain, Europe and the United States, and in the past 10 she has combined this varied career withworking with a number of bodies promoting economic development in Northern Ireland, being a member of the Department of Trade and Industry's advisory panel for deregulation and serving as a governor of the Harris City Technology College.
Professor Birley is adamant that each feeds off the others: teaching benefits from her practical experience while the business enables her to test theories. "My focus is entrepreneurship and I happen to do it in different guises," she says. Moreover, she maintains that "where I am physically at any one time isn't an indication of anything".
The only girl from her year at a mixed grammar school in Lancashire to go to university, she started as a mathematics specialist, but moved on, first, to statistics and then strategy "because I wanted to do something different". The result, she says, is that she has both a command of detail and the ability to see the wider picture.
Her interest in entrepreneurs has developed through teaching stints at institutions in several countries and this expertise has no doubt attracted the interest of NatWest, which claims to be the leading lender to the small business sector.
But Professor Birley, who will join the bank's remuneration and audit committees and be the bank's only female director when former minister Baroness Young retires at April's annual meeting, is unlikely to limit herself to this sphere. She thinks strategy and small business issues are closely linked and also believes large organisations can learn from smaller counter-parts.
"People assume you start a business and grow it, but don't think about what happens next. Industry is a bit like an amoeba, constantly changing."
General attitudes are changing, too. After her teaching experience in the US she agrees with the general contention that there is greater acceptance of enterprise and tolerance of failure across the Atlantic.
But she points out that because Britain was hit by unemployment earlier than most of its competitors, it was among the first countries to grapple with settling up enterprise agencies and the like.
Not all have been successful, but, as she says, "people are more interested in and aware of the option of doing their own thing, being their own boss, buying into a business. And this is not just because the threat of unemployment is clearly there. It's also because it's now accepted as a fun and exciting thing to do."
The bank, which last week reported a 10 per cent increase in pre-tax profits to pounds 1.75bn, has signalled one change, since the planned purchase of Gartmore is seen as a precursor to other moves in the fund management and life insurance field. But Professor Birley also sees developments in other areas, notably the already fast-moving retail banking sector.
One of her contributions will be to look at the information about the various businesses. "I will need to get a feel for the data - to roll around on the ground just to get a feel of how it works," she says. So much for the theory. She also sees her own business experience having a key impact. "The value of Newchurch [her consultancy] is that you know what it's like to be a founder of a business and to write personal guarantees and to raise venture capital. We've gone through all the growing pains."
Such a background also gives her valuable insights into the controversial topic of late payment. "Late payment is a serious issue for any business, but the impact on smaller ones is usually more because they are less stable. In some cases they are paid late because they invoice late, or they don't chase or the clients don't pay. You need to understand the simple things, such as if you don't get an invoice to the client before the date at which they do the invoices you lose a month."
It is the sort of forthright, no-nonsense talk that is likely to endear her to NatWest colleagues when she joins them on 1 March. Equally, her lack of sentimentality might disappoint those who think that because she has joined that select group of women who have penetrated the old boys' club of the City she will become a champion of female promotion.
Pointing out that she does not believe in positive discrimination, she says: "The female thing isn't my area. I don't think of myself as a woman professor. I get on with it. I've not encountered any problems."
She accepts that not having any children - she has step-children through her 20-year marriage to David Norburn, director of the Imperial College management school - has made a difference.
But, true to her academic calling, she has a statistical explanation for the dearth of women in the boardroom.
When Professor Birley, 52, was starting out few women were going on to higher education and embarking on careers. Consequently, she says: "There's what's called a supply issue which will take time to work its way through the system. The situation will change as the supply base changes."