An unclaimed £63.8m EuroMillions jackpot ticket was bought in Hertfordshire, the National Lottery has revealed.

Its holder has still to come forward to accept the windfall, nearly a fortnight after the draw.

There were two jackpot winning tickets on 8 June, one in Belgium, whose owner has come forward, and one in the UK.

The ticket was bought in the Stevenage and Hitchin area with numbers 5, 11, 22, 34 and 40, lucky stars 9 and 11.

The lottery team visited Stevenage this morning with two giant billboards mounted on trucks, reading "Are you the lucky £63.8 million winner?".

They are spending the afternoon touring the Hitchin area.

According to lottery rules, the winner has a 180-day deadline to pick up the prize, meaning they must come forward before 5 December.

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."

The money, if unclaimed, would go to the National Lottery Good Causes fund.

That happens here a lot.  When there is a big pot and it has one winner sometimes the winner lays low until the brouhaha dies down and they talk to a financial expert to they can do what is best to maximize the winnings.