Winners have 180 days to come forward to claim their prize

No-one has yet claimed the �20m windfall for which the winning ticket was bought on 14 July.

National Lottery operator Camelot said the deadline for the ticket-holder to collect their winnings was 10 January 2005.

The winning numbers are 6, 27, 33, 38, 45, 47.

Camelot is keen for the winner to collect their prizes as soon as possible as they are missing out on �2,200 a day in interest.

The exact amount of the unclaimed rollover draw prize is �20,100,472.

Wherever they are, there is still time to claim, so I would urge all Lotto players to go through old receipts, dig in pockets, search down the back of the sofa - you never know what you might find Jacquie Wilson Camelot

If the ticket was bought by an individual rather than a syndicate, the winner will be the biggest in the lottery's 10-year history.

Camelot's Jacquie Wilson said it was an amazing amount of money and they were working very hard to find the winner.

"Although the ticket was bought in Northern Ireland, the winner could be from anywhere in Britain," she said.

"Perhaps someone was enjoying an early summer holiday, or maybe the lucky ticket-holder was over on business when they made their lucky purchase.

"The second half of July is also the start of the holiday period for Northern Ireland, so it could be that the winner has simply been away for a few weeks.

"If that's the case they're in for a wonderful surprise on their return.

"Wherever they are, there is still time to claim, so I would urge all Lotto players to go through old receipts, dig in pockets, search down the back of the sofa - you never know what you might find.

"We have the champagne on ice and all I need now is a name to put on that cheque."

To date, former Belfast bus driver Peter Lavery was the biggest lottery winner from Northern Ireland.

He won more than �10m in 1996.

In April this year, a �14.2m lottery winner from Wiltshire finally came forward more than a fortnight after scooping the prize.

Winners have 180 days to come forward to claim their prize before the money goes into a fund to benefit good causes.

The Wiltshire winner missed out on about �20,000 interest for the days the prize was unclaimed.