Let’s get this straight. The Halifax is not trying to upstage Premium Bonds, the state-run lottery where savers gamble with the interest on their money. These days the Bonds are less of a lottery, more a way to make a tiny tax-free return on savings of up to £30,000 (most of the prizes are £25). The chances of winning the £1 million monthly prize on a single bond are worse than 40 billion to one, so if you don’t win the jackpot after four billion years (roughly the age of the earth) then you’re rather unlucky.

The total amount paid out in prizes is currently a miserable 1.5% a year, so you’re probably better off with, say, the Halifax and its easy access on-line account (easy access only to you, we hope) paying 2.8%. Still, there’s £42 billion sitting in the bonds, and Lloyds, the Halifax’s parent, wants to pull some of it out. Each month its Savers Prize Draw will pay £100,000 to three lucky savers, £1,000 to 100 more, and £100 to a further 1,000, a total of £500,000. You need at least £5,000 in the account, and you must register to play.

These winnings, somewhat surprisingly, escape tax, but a glance at HMRC’s rules rather gives the game away. Prizes in competitions organised “for publicity purposes” are tax free.Were Halifax to take all the 2.8% interest and dish it out to a lucky few, the taxman would take a different view.

If you’re quick to pay in your £5,000 and register, you would have a very small, but not trivial, chance of winning. However, Lloyds Banking Group is an enormous beast, and half a million is literally a rounding error on its balance sheet. The Halifax had £216 billion in customer deposits at the end of last year, so while the chance of the jackpot is better than one in 40 billion, it’s not much better. Oh, and that 2.8% is taxable, of course.