Lottery organisers took to the streets today as they stepped up the hunt for a mystery millionaire.
The unclaimed £63.8 million EuroMillions prize has been narrowed down to a ticket bought in Hertfordshire.
Its holder has still to come forward to accept the windfall, nearly a fortnight after the draw - the longest such a large win has gone unclaimed.
Two ticket holders hit the jackpot on June 8 - one in Belgium and one in the UK.
The owner of the British ticket, bought in the Stevenage and Hitchin area, will claim £63,837,543.60.
Today shoppers in the Market Square, Hitchin, were greeted by two giant billboards, mounted on trucks, reading "Are you the lucky £63.8 million winner?".
Crowds gathered around and the mystery was the talk of the town.
Pete Ware, 34, a street cleaner from Stevenage, said: "I play the lottery and haven't checked my ticket yet. I'll have a look when I get home tonight.
"If I won I'd buy a big car and a house and treat my parents."
Student Josephine Duncan, 16, from Stotford, Bedfordshire, said: "I've played the lottery a few times but haven't even won a tenner.
"If I won I'd treat my family and spend the money on horses for myself."
IT worker Sunny Nahal, 34, from Hitchin, said he had checked his ticket already.
"Sadly I don't think I'm the winner," he said.
"If I was, I'd be on a plane out of here by now."
According to lottery rules, the winner - who could be an individual or a syndicate - has a 180-day deadline to pick up the prize, meaning they must come forward before 11pm on December 5.
A Camelot spokesman said: "We're desperate to find this mystery ticket holder and unite them with their winnings and we're urging everyone to try checking 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.
"We have the champagne on ice and our fingers crossed that the lucky winner comes forward to claim their win."
If the ticket holder fails to come forward, the money - and the interest it has generated - would go to the National Lottery Good Causes fund.
The prize pot came as a result of a double rollover.
Camelot can make a pay-out, at its discretion, where a ticket has been lost, stolen or destroyed - but only if a claim is submitted within 30 days of the draw and if there is sufficient evidence.
The winning numbers were 5, 11, 22, 34 and 40 with the lucky stars 9 and 11.
The lottery team visited Stevenage this morning and will spend the afternoon touring the Hitchin area.