That got you, didn’t it? No such thing, you may say, but you’d be wrong. Bargain investments don’t stay on offer for long, and this one will not last beyond the end of next month. Fortunately, it’s not restricted before then, and while realising the gain will take time and a little effort, this is not an early April Fool.

The investment is stamps; not those bits of paper that Stanley Gibbons keeps telling us only rise in value, but common British first and second class letter stamps, which are guaranteed to. From the end of April, the price of each rises by 14p, to 60p and 50p respectively. That’s an increase of 30% and (gulp) 39%. It’s a long way from the Penny Black to 12 shillings (144 times dearer) and the move will inject a shot of cash into the Royal Mail balance sheet as people stock up. Following the prestigidation with the company’s pension scheme, it will make the business look prettier for next year’s mooted privatisation.

It also gives the public the chance to make a turn. Buying a few ahead of the price rise will save a little; buying a serious quantity could make you enough to enjoy free postage for quite a while. After a rise like this, there’s bound to be a lively secondary market of stamps discounted from the new price. You’d have no trouble arranging delivery (though settlement might be trickier) but as with all stockpiling, you must resist the temptation to use more than you would otherwise. So get stuck in (or on).