A couple from Suffolk have claimed last week's massive £148.6 million EuroMillions jackpot, the National Lottery has said.
The windfall will make the pair the nation's second richest lottery winners.
But they are keeping their identity a secret until Tuesday when they are expected to go public and reveal their plans for the future.
The couple, from the town of Haverhill, were the only winners in Friday's draw and scooped a staggering £148,656,000.
The sum is just behind the £161 million landed by Colin and Chris Weir, from Largs in North Ayrshire, last July. A difference in the exchange rate means this week's jackpot was slightly lower.
A National Lottery spokesman said: "A couple from Haverhill, Suffolk, have won the UK's second biggest ever lottery prize.
"They were the only winners in Friday's EuroMillions draw and have banked an amazing £148,656,000."
Theirs is the seventh lucky ticket to have hit the jackpot in the UK this year.
To date, the National Lottery has created some 2,900 millionaires.
Friday's winning numbers were 50, 21, 17, 48 and 11, and the Lucky Star numbers were 09 and 10.
The map was commissioned to mark Tuesday night's EuroMillions roll-over which is now a staggering £138 million - the fifth biggest jackpot ever offered in the UK.</p>
Should anyone scoop the jackpot, their wealth will be slightly less than Europe's biggest Lottery winners Colin and Chris Weir, from Largs in Ayrshire. The husband and wife made the headlines in July when they won £161,653,000, thanks to several rollovers.</p>
Boasting 164 National Lottery millionaires, one in 14,211 North East residents has now banked a seven-figure jackpot prize. Winners Paul and Christine Goldie from Washington, near Sunderland, pocketed £3,581,481 after their numbers came up on Christmas Day last year.</p>
The Millionaire Map, which includes both publicity and non-publicity winners, is based on the number of millionaires created per adult population. One man who did go public with his winnings was Wayne Hughes from Holyhead on Anglesey, north Wales. The shop worker scooped £1,117,779 last August and even had the winning numbers tattooed on his arm.</p>
The region with the fewest millionaire jackpot winners was Northern Ireland, where only 53 seven-figure or more winners were created.</p>
Wales has seen 179 millionaires - one person in 14,502 - created over the last 16 years. Rugby fans Terry Roberts, Mike Williams, Lance Gifford and Gerwyn Jones, from the Rhondda Valley in south Wales, split £4,091,609 in April this year.</p>