In London, there are over 190,000 unclaimed Premium Bond prizes worth £7.8m, with a £25 prize dating back to December 1958.

The highest unclaimed prize is worth £50,000, and was won in May 2016. It belongs to a woman who currently has £9,175 invested. Five prizes of £10,000 also remain unclaimed.

In Kent, there are over 39,000 unclaimed Premium Bonds prizes worth over £1.5m, the oldest being won in April 1959.

Premium Bonds prizes may go unclaimed as a result of NS&I not being informed of changes to personal circumstances, such as changes to contact details or addresses.

You can check if you have won using the Premium Bond prize checker.

Administered by National Savings & Investments (NS&I), Premium Bonds are much like savings accounts, but with one big difference: instead of a reliable interest rate your returns are determined by a monthly lottery.

While the bonds themselves don’t earn any interest, the annual prize pot, which is currently 1.25%, is used to fund the monthly prize draw. The gains on Premium Bonds are tax free.

The odds of each individual bond number winning any prize are 30,000 to 1.