A £63.8m EuroMillions jackpot prize will be given to good causes after the winning ticket holder failed to come forward before the deadline.
The winning ticket was bought in the Stevenage and Hitchin area of Hertfordshire on 8 June and its owner had until 11pm on 5 December to claim the prize.
The money will be added to the amount that goes to good causes from National Lottery ticket sales, which typically totals more than £30m a week.
People from nine countries, including France, Spain and Switzerland, can buy tickets to play the EuroMillions game, but the unclaimed prize will go to UK good causes because the unclaimed ticket was bought in the UK.
In 2011/12, £105m in prize money from all National Lottery games went unclaimed, which was 3 per cent of all prize money. All of this went to good causes – it represented 6 per cent of all good cause money over the year, which totalled £1.8bn.
A National Lottery spokeswoman said: "Unfortunately, I can confirm that the ticket holder did not come forward within the deadline to claim their prize and has now sadly missed out on this staggering amount of money."
More than £29bn has been given to good causes since the launch of the National Lottery in 1994, and it has benefited more than 390,000 projects.