The winner of an unclaimed £63.8 million EuroMillions jackpot has failed to come forward despite public appeals in the area where the ticket was bought.
Camelot said no one had claimed the massive prize a day after lottery organisers took their hunt for the mystery winner into the streets of Hitchin, Hertfordshire.
The uncollected windfall is from the double-rollover draw on June 8 when tickets issued in Belgium and in Hertfordshire both hit the jackpot.
The British winner, who bought their ticket in the Stevenage and Hitchin area, has still to come forward two weeks later, the longest period such a large win has gone unclaimed.
Giant billboards mounted on trucks bearing the question "Are you the lucky £63.8 million winner?" were paraded in Hitchin's Market Square.
The winner, who could be an individual or a syndicate, has a 180-day deadline to pick up the prize, meaning they have until 11pm on December 5, according to lottery rules.
If the ticket holder, with winning numbers 5, 11, 22, 34 and 40 and lucky stars 9 and 11, fails to come forward, the money and the interest generated will go into the National Lottery Good Causes fund.
A Camelot spokesman again urged people to "triple-check" their tickets.
Earlier this week Camelot urged those who have bought tickets in the relevant 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 Camelot spokesman said.