The Lotteries Commission has tracked down the winner of almost $23 million in a recent Big Wednesday draw.
It says it found the winner by establishing the day, time and place the ticket was bought.
Commission spokesperson Emilia Mazur says they then had a bit of good luck although she would not say what that was, citing privacy.
She says the winner had been told by a workmate the draw had already been won and he had not bothered to look at his his ticket.
He was sceptical at first when Lotteries staff told him of his good fortune, but after checking his ticket, began to celebrate, saying he would live off the interest and build his dream home.
She says the 25 September draw yielded the biggest ever Lotto win in the South Island.
Ms Mazur says it is very rare for such a large prize to go unclaimed for so long, but the commission will try to track winners down if they have enough information to do it.