At the dinner, South African President Jacob Zuma, international government officials and former protesters spoke about the party's history, at one point noting New Zealand's involvement in the international campaign.
Mr Wickham said the anniversary was momentous, particularly for those who had been involved in the movement as long as he had been.
"We thought, even right through to the '80s, we'd never live to see the day we'd get [Nelson] Mandela out of jail," he said.
"It'd be hard to find another liberation movement that's lasted for 100 years, and I think that's enormously significant and hugely worth celebrating."
The party has led the country and maintained huge support since 1994, although has been somewhat divided by infighting, most recently with youth leader Julius Malema being suspended.
Mr Wickham said the controversy came from those who were not satisfied with the progress being made, specifically relating to housing, education and jobs, and that those people were not properly taking into account what the ANC was up against.
"The problems that the ANC have faced - people have just got to be realistic about it."