He said: “The more bonds you have, the closer you get to the prize fund rate, and this is where the scales start to tip in Premium Bonds’ favour.”

This is because each bond is purchased at £1 and like any lottery the more one buys the higher one’s chances of winning.

There are an estimated 21 million bond holders currently in the UK, many of which reinvest any winnings they receive to buy more bonds.

With over 3.3 million other prizes being paid out this month, worth between £25 and £100,000, Britons are being urged to check to see if they have won in this month’s cash prizes