A lottery winner has 13 days left to claim a prize of £260,536.
The person, who bought the ticket in North West Leicestershire, has until 11pm on August 15 to grab the winnings.
The ticket matched the five main numbers and the bonus ball number on the lotto draw on Saturday February 16.
A National Lottery spokesman said: "Time is running out for the winner of this prize, but we are still hopeful someone will come forward.
"We are urging everyone to check their old tickets one last time or look anywhere a missing ticket could be hiding.
"This life-changing prize could help make dreams become a reality for someone."
The numbers drawn were 7, 20, 27, 39, 46, 48 and the bonus ball number of 49.
If no-one comes forward with the winning ticket before the deadline, the prize money, plus all the interest it has generated, will go to National Lottery Good Causes.
This search for a winner comes just days after a winner who bought a ticket in the borough of Hinckley and Bosworth failed to claim £262,109.
That person had until 11pm July 31 to claim the money.
A National Lottery spokesperson said: "Unfortunately, I can confirm the ticket-holder did not come forward within the deadline to claim their prize and has now missed out on this substantial amount of money.
"To avoid this unfortunate situation happening again, I would urge all National Lottery players to check their tickets on a regular basis.
"We tried very hard to find the ticket-holder.
"It is a real shame that they have missed out, but there is still one winner – the nation."
The Mercury reported in May that 13 millionaires were created in Leicestershire in the past two years by the National Lottery, making the LE postcode the eighth luckiest out of 121 during the period.
But it was not so lucky for some as three prizes totalling £1.5 million were not claimed in time last year.
With all National Lottery tickets, players have 180 days from the draw to claim their prize if they have the winning numbers.
Anyone who believes they have a winning ticket for any of the draws within the past 180 days should call the National Lottery Line on 0845 910 0000.
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