Oxfam had always maintained that education should be left to governments and its director worried that Leggett would spend his whole budget building schools.
"I said, 'No I won't, I'll spend it campaigning for debt relief to build schools'. The amount of education infrastructure that has been built on the basis of debt relief in Africa is overwhelming compared with anything Oxfam could have done by itself."
All the major UK campaigns for global social and economic justice have Leggett's prints on them. Jubilee Debt, Trade Justice Campaign, and Make Poverty History have all reinforced his view that things can only change there if they change here first.
The involvement of Leggett's comparatively tiny student campaigning body People & Planet alongside big fish like Greenpeace in the new, provisionally named Climate Movement (see p1), is testament to his reputation as a campaigner.
But while that campaign will dominate People & Planet's work for three years, Leggett is embarking on a parallel crusade.
He is on a mission to mobilise more people to rattle more establishment cages, and to ensure that smaller campaigning organisations can get the resources to help them. How? He aims to persuade the Government and the Charity Commission to recognise that campaigning delivers public benefit.
Leggett contends there is no better demonstration of this fact than this weekend, when Make Poverty History campaigners will converge on Edinburgh and shine a spotlight on the leaders and policies of the rich world. While debate rages on within the sector about whether Make Poverty History has become too tame or been co-opted by New Labour, at the popular level it has been a great success.
"It has appealed to ordinary punters and that is a huge step forward," he says.
Yet far from being able to capitalise on this, People & Planet and other small campaigning groups are hamstrung by their inability to access funds from Government, or from trusts and foundations.
Leggett says charities that deliver poverty-reduction projects overseas or work with marginalised groups in the UK can usually find funds. "But if you are concerned with global justice and you know that to achieve fundamental lasting change on poverty and the environment we need to change our policies and our way of life in this country, you can get almost no money at all.
"I would like to see it made crystal clear in the Charities Bill that campaigning on established debates is absolutely legitimate.
"This year, as we debate a new framework for charities, we should be legitimising the role of activism, so people can take action to hold their government or corporations to account to achieve agreed global objectives such as the Kyoto Agreement. Raising awareness and understanding of development issues only gets you so far - doing something to change the world is what counts."
Leggett concedes that without the lobbying capacity of bigger agencies such as Oxfam, he faces an uphill battle. But he is doing the groundwork: as well as raising the issue in the media, he is ensuring the debate reaches grantmakers with the recent appointment of Institute of Fundraising chair Joe Saxton as chair of People & Planet. He denies it is a long-term campaign, though. "I'm not particularly patient."