After 50 of my choices, the final episode of the series has been down to you.

Loyal podcast listeners have made hundreds of suggestions and cast many thousands of votes

for our short list of six. Thank you so much. We've been overwhelmed by the ideas and the

interest that you've shown. So now...

It's time to unveil your choice.

The 51st thing that made the modern economy with Tim Harford.

The clue is in the name...

Quedet.

It means belief. Trust. If you're a shopkeeper, who do you trust to repay a debt?

For most of history, only someone you personally knew. And for most of history,

it was fine since most of the people you encountered would be from the same small community.

Everyone knew everyone. If a customer lets you down, you could complain to their mother about

them in church on Sunday. But as it is boomed, things became more awkward.

Large department stores couldn't rely on employees to recognise every customer by site.

So retailers issued tokens to the customers they trusted. Special coins. Key rings.

And in 1928, even objects resembling dog tags called Charger Plates.

Show one of those and a shop assistant who didn't know you would happily let you walk

out of the store with an armful of goods you're not yet paid for. Perhaps,

revealingly, some of those credit tokens became status symbols. They signified I,

and the kind of person that is trusted.

In 1947, came the first token that allowed someone to get credit, not just from a single store,

but from a range of stores. The Charger. Admittedly, this worked only within a two-block area of

...