The National Lottery said they were "desperate" to find the mystery ticket-holder who bought their ticket in Bradford for the draw on Saturday October 5.
The winning Lotto numbers were 5, 15, 17, 19, 20, 47 and the bonus ball was 38 but the clock is ticking as the winner has until April 3 2014 to make their claim and join the multi-milionaires club.
"We're urging everyone who may have bought a ticket in this area to check in the pockets of clothing, in wallets, bags and down the back of the sofa - someone out there could literally be sitting on a fortune, " a spokesman said.
"We have the champagne on ice and our fingers crossed that the lucky winner comes forward to claim their win."
A key reminder for anyone who thinks they may have scooped the jackpot is that this winning ticket was bought for the draw which marked the launch of new Lotto game.
It saw a single ticket-holder scoop the guaranteed £10 million jackpot and 1,000 players won £20,000 each in the new raffle.
A giant ad van displaying the information about the ticket stood at Bradford City Hall, Centenary Square, before heading off around the area.
If no-one comes forward with the winning ticket before the April deadline or has submitted a written claim stating their ticket has been stolen, lost or destroyed, then the prize money along with all the interest it has earned will go to The National Lottery Good Causes .
Thirty billion pounds has been raised through lottery tickets sales since The National Lottery launched in November 1994.
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