"All South Africans stopped what they were doing to mourn Mandela," he said.
The challenge now was for a new leader of Mandela's stature to step up in the May elections.
"Mandela was a symbol of a better future for South Africa and now there is a vacuum of hope that needs to be filled by a leader."
Mr Searell said cities such as Pretoria were developing rapidly: "A hub of finance, where you see Mercedes and BMWs parked in the street."
On New Zealand's relationship with South Africa, Mr Searell said trade was modest because of the transport costs involved.
"There are no direct flights and ships have to stop in Singapore."
New Zealand annually exported about $225 million in goods to South Africa, with dairy exports making up the bulk of sales.
Mr Searell said sport still played an important part in the relationship between the two countries, initially because of the 1981 Springbok tour and the role that had in addressing apartheid, but it also had an ongoing role in bringing people together and forgetting racial differences.
The talk took place at the Sport Wellington Wairarapa complex on Chapel St and was part of a series hosted by the New Zealand Institute of International Affairs.