Mrs Vaz won her award for her successes as director of BT's payphones division, and is the first corporate ladder-climber, rather than entrepreneur, to be chosen.
But the accolade still doesn't mean as much to her as becoming a Level Two manager at BT after entering the company as a clerical officer.
"It was the first time I'd reached a graduate grade. Luckily, my mother lived to see it, but she knew I could have been there more than ten years earlier if I'd gone to university as I was supposed to."
Mrs Vaz, 48, sitting in a borrowed BT office wearing a blazer and a favourite arrow-shaped brooch (she points it downwards when people irritate her), knows what drove her struggles for promotion.
"I was still trying to make up for those failed A levels," she confesses. BT was her third attempt at a career after grammar school in Canterbury ended with only one A level. "I did well at O levels, then played too much netball and tennis and didn't work." It is not a mistake she has repeated since.
"My mother was hugely disappointed. She was deputy headmistress of a junior school, from quite a hard-up family, and her brothers had left school at 14 to put her through college."
The disgraced daughter was articled to a City firm of chartered accountants. She disappointed her mother again by marrying very young and having her one child, Donovan.
Articles were abandoned in favour of a better-paid job as bookkeeper to the Printing and Kindred Trades Federation, a group of print unions. Here, Mrs Vaz made herself useful around the edges of her job description, expanding her role to include administration and minute-taking at wage negotiations.
That was how she picked up the invaluable ability to see through male posturing. "It was amazing how union officials' behaviour changed when they got to the negotiating table. I could see when people's egos just needed to be stroked." It was experience which came in useful when she stepped into senior management at BT amid the 1987 engineers' strike. Meanwhile, she was working full time and Donovan was being looked after by an devoted childminder.
The print unions fell out with one another, Mrs Vaz's carefully expanded empire disappeared and it was back to square one. In 1975, at 28, she joined BT, where her husband also works, at a less elevated level.
Her first job was in personnel, allocating Arctic underwear for staff on the Atlantic cable ships when BT was all forms in triplicate with On Her Majesty's Service on the bottom.
Promotion, she was told, meant waiting on a list for what could be 20 years, unless she transferred to the network side, which was said to be impossible. So she said she'd resign and rejoin, knowing this would force her manager to write a long, dull staff departure report. She got what she wanted.
This seems to be Mrs Vaz's secret. "I do not find myself being confrontational. I try to find a way of avoiding people who are getting in my way. It's all about making your opponent's line of least resistance coincide with what you want."
She rose through the "softer" functions like marketing but also the engineers, the all-male core of the by now privatised BT. She chose to ignore rather than confront any sexual innuendo.
"I always like to be treated as a lady, though," says Mrs Vaz, sounding slightly headmistressy. "I like a man to stand up when I come into a room." But BT has a strong corporate spirit. What about all that laddish work socialising many female executives feel they have to join in?
Mrs Vaz never went in much for drinking with the boys. "I had a house to go to and meals to cook. I have often wondered what would have happened if I had involved myself more in relationship-building and networking." After becoming district engineering manager for Kent and East Sussex, she was sent in 1990 to head up BT Payphones, then losing £46m a year.
The callboxes' infuriating tendency to go on the blink just when you needed them most was already falling from an average of 30 faults a year to about 16. However, it is Mrs Vaz who is officially credited with getting faults down still further, winning back the Post Office and Forte accounts and turning loss into a £74m profit last year.
Mrs Vaz has now moved on to become director of Breakout, BT's continuing review of it basic procedures and practices. She is a member of the group quality control and reports to Dr Alan Rudge, deputy group managing director.
However, she is still very interested in BT's 130,000 payphones, which she is convinced can withstand the threat posed by Britain's growing mobile phone population, which already has more than three million units.
"A payphone offers inherent advantages such as weather protection and privacy. We have been planning initiatives in using them for data and fax transmission," she said.
She admits to failure, however, when it comes to ridding central London's payphones of prostitutes' calling cards, which she recognises many users find threatening or upsetting.
"Even phoning prostitutes with warnings is difficult because their lines are continually engaged - think of the revenue they bring BT. We tried legislation but the House of Lords threw it out, which was interesting," she adds with a quite unheadmistress-like snigger at their lordships' sympathies.
"We clean the payphones as often as we can but even the ones across the road here" - she points to the callboxes between BT headquarters in Newgate Street and St Paul's Cathedral - "fill up with cards after ten minutes. I'm sorry, but I have failed." Her track record suggests, however, that failure will not be the last word.Reuse content