Popular and long-serving Grey District Mayor Tony Kokshoorn will retire from politics at the local body elections next year.

The Grey District's longest-serving mayor will retire next year after two decades in politics.

Tony Kokshoorn has held the role since his landslide win against incumbent Kevin Brown in 2004 and has been elected unopposed four times.

Before becoming mayor, he served six years as a councillor in the district, which runs from Punakaiki to south of Greymouth on the West Coast.

He retires short of catching New Zealand's longest-serving mayor Tim Shadbolt, who is in his eighth mayoral term. His right-hand man and the country's longest-serving councillor, deputy mayor Doug Truman, lost his seat after 48 years in a shake up of West Coast councils last year.

Kokshoorn said he had seen "huge change" in the district during his tenure. Thousands of coal mining jobs had dwindled down to a few dozen and hundreds of tourism roles took their place.

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The council had invested more than $130 million in infrastructure upgrades, including new sewerage schemes, a new aquatic centre, the international-grade Westland Stadium, and the Greymouth town square.

He has also raised more than $30m for West Coast charities; chaired many trusts, including the SPCA Fundraising Committee; and rocketed into the top 10 of the Reader's Digest's "most trusted New Zealanders" poll in 2011.

But his time will be marked most by the 29 men who died in the Pike River Mine explosion in November 2010. Kokshoorn said the disaster, coupled with the collapse of the coal mining industry, was an "extremely challenging" time for the district.

"I still remember when I got the call. I was going about my duties and I went to pick my wife up … they told me 25 to 30 people were missing and I knew the repercussions of that.

"There's no handbook for that kind of thing, no-one to tell you what to do. It was all off-the-cuff, I just had to get there and stand by the families."

He was flung into the national limelight, fronting cameras day after day during the aftermath of the disaster. He also chaired the Pike River Disaster Trust and Pike River Memorials Committee, which raised and distributed $8.3m in 2013.

"The despair was terrible, I'll go to my grave with that wailing and the sadness. That's when you know you have to step up to the mark."

The former used-car salesman and was a finalist in the 2010 New Zealander of the Year awards, but did not care much for accolades.

"Lots of people have good ideas, and that's important, but what's really important is putting a hat on the idea, rolling your sleeves up and getting on with it.

"I could've put my feet up and cruised along, but I've never been that kind of mayor; I'm a driver person, I've worked extremely hard."

Kokshoorn held the economic development, finance, port, public relations and tourism portfolios for the district.

He said he announced his retirement early so there was plenty of time before the 2019 local body elections to form a succession plan.

The eldest son of a Dutch immigrant father and a West Coast mother, Kokshoorn spent the first five years of his life in Ruru – a small sawmilling town near Lake Brunner. He moved to Greymouth before starting at Marist Brothers Catholic School. He has retained a firm connection to his faith.

A trained automotive engineer, he holds a 50 per cent shareholder in Greymouth Car Centre, which he started in 1981 with his brother Dave, and is a 40 per cent shareholder in West Coast newspapers, including the daily Hokitika Guardian and weekly West Coast Messenger.

Charity work has played a huge role in his career. He was a founding trustee of the Grey District Young Persons Development Trust and the Life Education West Coast, and was trustee of Dixon House for the elderly.

He will turn 65 soon after he steps down from the mayoralty and is looking forward to spending more time with wife Lynne, their four children and two grandchildren.

"No man is an island. You've got to know when to fold and give someone else a chance to pick up the gauntlet. I'm sure I'll find something else to do, I've no doubt."