A syndicate from Bournemouth who have played the National Lottery game for 10 years win £500,000.
The mystery winner bought the ticket in Wolverhampton for the 27 March draw.
The 15 winners, formerly finance colleagues, made a pact to stay connected by contributing £5 to the lottery draw.
The funding will be granted over three years to The Pearl Exchange, which supports young people.
The Earls Colne Heritage Museum will be bought and modernised with the funds, its manager says.
Sean Hayes describes finding out the news in the pub, and he now plans to buy a house.
The new museum will be home to more than 600 field guns, howitzers, mortars, rockets and medals.
The unclaimed ticket was bought in Bexley and matched all six main numbers in the 4 October 2025 draw.
Tuesday's win is the third-largest in UK National Lottery history, operator Allwyn says.
