Michael Erceg is a Westie wunderkind. With a personal fortune conservatively estimated at $600 million, the businessman with a PhD in mathematics is the second richest man in Auckland, at number five on the National Business Review's Rich List.

A former Kelston Boys High pupil, Erceg made his fortune from his discount brewing and distilling business, Independent Distillers Group, most famous for its budget "RTDs" such as Woodstock Bourbon and Colas and Vodka Cruisers.

Erceg started the business in Papakura in 1987, and is now regarded as the man who injected competition into New Zealand's alcohol industry. But with a PhD in mathematics, Erceg was not your typical liquor baron. The academic-turned-alcopop king is described by friends and business associates as intensely private, reclusive and an "enigma", dedicated to his work and family.

Born into a close-knit Croatian wine-making family with an 80-year history in Waitakere, Erceg was one of four children. They grew up in a small brick house on a modest Henderson street, next door to the headquarters of the family business, Pacific Vineyards. Everyone knows everyone, especially the Ercegs, on this street.

His mother Millie still lives there, his father passed away some years ago. Brother-in-law Frank lives just down the road. His brother, Ivan, is a yacht-maker and owns Sensation Yachts, his sister Vinka lives in Mt Eden and is married to a prominent businessman. Erceg lost his eldest sister Marieanna and close confidante to cancer a couple of years ago, a devastating loss for the family.

Erceg was a top pupil, skipping sixth form and was awarded Dux of Kelston Boys High School in 1972. He earned his PhD nine years later, from the prestigious University of California in Berkeley, and went on to teach maths at university level in America.

But when his father Mick, a well-respected wine-maker, became ill in the mid-1980s, Erceg returned to help run the family business. A handmade sign written and signed off by Erceg hung on the headquarters window yesterday. It says Pacific Vineyards is no longer open for business. Neighbours say they think it has been sold or moved.

A few years after his return, Erceg started Independent Liquor, now known as Independent Distillers Group, and never looked back.

His quick-thinking, analytical mind and fair, reasonable manner saw him cope with the ups and downs of life in the alcohol industry. Independent Liquor now has a 65 per cent share in the RTD market, exports to 70 markets, has branches around the world and has now become a serious a real competitor to Lion and DB with the move to brew upmarket Danish beer Carlsberg.

This, it was said, was to be Erceg's golden year.

He married late in life and has a stepson with his wife Lynnette. It is understood his son works at Independent Liquor's UK branch. With properties and interests in vineyards in Queenstown and Nelson, Erceg resides in a villa on a 35ha block in Papakura, South Auckland, valued in 2003 at $2.1 million.

Despite being one of New Zealand's most highly respected and successful businessmen, little is known about Erceg. He rarely granted interviews, talking about his work rather than family when he did, and has successfully avoided the cameras. All Black coach Graham Henry is a close friend.

Flying his near-new helicopter was a hobby and preferred mode of getting around for a man who spent much of his time travelling for work. Yet friends maintain Erceg is a modest man, seemingly averse to flaunting his immense wealth.

Colleagues say Erceg will not suffer fools or step down from a challenge.

He has never been afraid to rail against what he sees as government stupidity. In 2003, when Associate Health Minister Jim Anderton increased the excise on drinks with an alcohol content 14-23 per cent, Erceg released a range with a 13.9 per cent alcohol content. He said it was in part a move simply to annoy Anderton.