Then the tech bubble began to burst in 1999 and there was a lot of angst at the time about how to help people have a richer retirement and greater savings, says Altmann.
For instance, she was involved in launching child trust funds in 2002, which were designed to provide youngsters with a nest egg when they start their adult life and encourage them to develop a better savings habit.
"That was all about marrying the idea of long-term investment returns helping people avoid poverty, or improving their incomes," she says.
Meanwhile, she took the government to court over flawed laws that meant members of underfunded pension schemes at insolvent employers were at risk of losing their pension funds.
The “pensions theft” scandal saw tens of thousands of members of final salary schemes lose all or part of their promised pensions when their employers collapsed between January 1997 and April 2005.
The case started off discussions that led to the establishment of the Financial Assistance Scheme and Pension Protection Fund, the former of which Altmann was critical.
She describes the case as a "shock to the system" that showed "you couldn't just rely on the actuarial assumptions and that you needed a safety net for the worst outcomes".
In 2010 Altmann became director general of over-50s specialists Saga and chaired several investment-related boards, before being invited back to Whitehall as the government's business champion for older workers.
"That work led to me doing more and more with the coalition government and then suddenly in 2015 I get a phone call from George Osborne," she says.
"He said, 'Could you come in to Downing Street tomorrow I need to ask you something urgently. David Cameron and I want to speak to you'."
She was offered the role of pensions minister should the Conservatives win the next election – something that seemed unlikely at the time. She declined, saying Steve Webb would be the man for the job. Besides, she did not think the Conservatives would win again, at least not outright.
When they did however win, she was made pensions minster, "unfortunately!", she exclaims. The self-professed politics novice, who did not want to work in the Department for Work and Pensions to begin with, relented because she was a fan of Osborne's pension freedom reforms.
But she suffered ongoing clashes with several colleagues and her boss over her pro-EU stance, which eventually led to her walking out.
"I felt as an economist that coming out of the EU was a terrible idea for all our futures," she says. "So I was very strongly campaigning for remain. That was at odds with my secretary of state in the DWP and most of the other ministers.
