What did he do? Co-wrote the single "Do They Know It's Christmas?" with Midge Ure, then persuaded a group of pop stars to sing it.
How much did Band Aid raise? £10m in the first six months, then another £100m until 1992, when the charity was shut down.
How was the money spent? On "grassroots" projects in the main. "Agencies proposing primary healthcare schemes, such as inoculations and encouraging good nutrition, were viewed more favourably than plans for, say, a high-tech hospital," explained Penny Jenden, former chief executive for Band Aid. "Africa is littered with the remains of tractors or drilling rigs that nobody knew how to mend."
Who decided how the money was spent? A committee of "experts" (academics more than practitioners) was formed in October 1985 under the chairmanship of Brian Walker of the International Institute of Environment and Development. The committee met monthly to assess and discuss more than a thousand projects, of which 189 were selected for funding.
Who benefited? "The poorest of the poor" in Ethiopia, Sudan, Mali, Chad, Niger and Burkina-Faso.
The largest single grant? $3m to buy vaccine for a UN child-immunisation programme for all six countries.
Were there critics? Iain Macdonald, Sudan's director of Euro-Action Accord 1985-1988, was one of the most vocal. He said: "They concentrated too much on not wasting money and missed a lot of high-risk, but high-need projects." Anthony Nedley, Oxfam's co-ordinator in Sudan, said: "They employed human dynamos with no secretarial support who ran round the country promising the earth, but who couldn't deliver because they had no logistics back-up. It was far too temporary, makeshift and lacking in structure to be really effective."
And on the bright side? "Bob Geldof brought in a new constituency of people eager to help - young people mostly. He kept Third World issues on the agenda," remembers Hugh Goyder, who was field director in Ethiopia between 1982 and 1986 and now works for Action Aid. As well as meeting emergency needs (extra resources and extra vehicles), Geldof was also "remarkably" far-sighted: "He concentrated a lot of the resources into long-term projects, such as building water supply schemes and health programmes."
Recognition? The Queen presented Geldof with an insignia of the Knight Commander of the British Empire in 1986. She said: "This is a small token for the work you have done." He said: "Believe me, it was harder work getting into this [Savile Row] suit."
How is Ethiopia faring now? Feeding stations were taken down in 1986, but four million of the 54 million population will still need relief aid next year - mostly people in rural areas.