As Mr Key went to leave the development a group of children converged around the prime minister and resumed the chanting. His ministerial BMW then appeared, which was egged as it whisked him away.
As police tried to move the group, one man was arrested for obstruction.
Earlier, Mr Key answered media questions about Shane Jones announcing he was quitting the Labour Party to take up a position created by the National-led Government.
Mr Key said he wasn't personally involved in the discussions and could not recall when he found out Mr Jones had been offered the role.
He added that Mr Jones had seen an opportunity, and had been an "effective'' Labour MP.
He also said Mr Jones was perfect for the job.