Key Points:

Former Christchurch mayor Sir Hamish Hay died aged overnight at the age of 80.

He was Christchurch's longest-serving mayor, serving five terms from 1974 until to 1989, when he stepped down.

Sir Hamish came from one of New Zealand's most honoured families. His father, philanthropist Sir James Hay, who founded department store and supermarket chain Hay's Ltd, received a knighthood and two of Sir Hamish's three siblings received high honours.

Identical twin brother, Sir David Hay, was knighted for services to medicine and health and his older sister, Dame Margaret (Laurie) Salas, received recognition for work for the United Nations and for the women's and peace movements.

Sir Hamish worked in the publicly listed Hay's, where he rose to deputy managing director, from 1962 to 1974. He stepped down when Hay's was taken over by Wright Stephenson & Co to become Haywrights.

His first foray into politics saw him top the poll for the Christchurch City Council in 1959 and he remained a councillor until 1974, when stood and won the election for mayor against Labour incumbent Neville Pickering.

A keen supporter of the arts, Sir Hamish was a driving force in the building of Christchurch Town Hall, where one of the theatres, the Sir James Hay Theatre is named after his father, who in his term as city councillor was also a strong proponent of building a town hall.

Sir Hamish was deputy chairman of the Sir Charles Upham Trust and chairman of the New Zealand Museums Trust which oversaw the controversial building of the national museum, Te Papa.

His autobiography, Hay Days, was published in 1989.

In recent years, Sir Hamish was affected by Alzheimer's disease. He is survived by his wife Lady Judith Hay and their five children.